Automatic voltage regulation in the generator. Generator operation and voltage regulator check

It is important to note that the field winding circuit includes a voltage regulator transistor that allows you to change the magnetic flux generated by the coil in order to ensure the stability of the generator output voltage. The setting voltage of the voltage regulator is selected based on the value of the rated voltage of the vehicle network and the existing consumers of electricity. The excess voltage of the regulator setting over the value of the rated voltage of the vehicle network is selected to compensate for the voltage drop in the wires so that for normal ...

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Automotive generator ny installation

L e c i

Automotive The generator set is a synchronous electric machine - the actual generator with a built-in semiconductor rectifier and voltage regulator. It is designed to power consumers of electricity in the car and charge the battery.

An electric machine is called synchronous, the rotational speed of which isproportionalthe frequency of the alternating current in its stator winding.

1.Principle of operation of the generator

The principle of operation of the generator is as follows.

With the ignition on and the engine running, current flows through the field winding and the rotor is a system of 12 magnetic poles of alternating polarity rotating inside the stator. It is important to note that the field winding circuit includes a voltage regulator transistor that allows you to change the magnetic flux generated by the coil in order to ensure the stability of the generator output voltage. That is, so that the output voltage does not increase with an increase in the rotor speed, it is sufficient to reduce the current in the excitation coil accordingly.

The stator windings are connected in a "star" (sometimes in a "triangle"), forming a typical three-phase system in which an EMF is induced. Please note that in a car with an EO which is designed for a constant voltage of 12 V, the generator is a generator alternating current. It becomes permanent after rectification by a diode bridge. Due to high currents (tens of amperes), the diodes of the rectifier bridge get very hot and, to protect them from damage, they are attached to a heat sink made of a heat-conducting aluminum alloy and blown by a fan.

In addition to the 6 rectifier diodes, the generator has three additional diodes, from which the voltage is removed to power the field winding in a steady state (at the beginning, the battery is used). They operate at low currents and do not need radiators.

At the output of these diodes, with an increase in the rotational speed of the generator rotor, the voltage and the potential difference between it and the positive terminal from the power diodes, which connected directly to the positive of the battery, decreases. The voltage on the test lamp goes to zero, and it goes out. This controls the operation of the generator.

The rotor revolutions at which the generator is self-excited are negotiated in its technical conditions (for a 2110 car generator, these revolutions are 1400 rpm). In order to reduce the self-excitation speed, the current passing through the rotor winding is increased by connecting a 50 Ohm resistor in parallel with the control lamp.

Voltage the voltage regulator settings are selected based on the value of the rated voltage of the vehicle network and the existing electricity consumers. Its value for a twelve-volt system ranges from 14.1 V to 14.75 V. The excess of the regulator setting voltage over the value of the nominal voltage of the car network is selected to compensate for the voltage drop in the wires so that for normal operation the voltage at the electricity consumers does not decrease below 12 V.

Basic characteristic of automobile generators is the current-speed characteristic, which is a dependence straightened current at the generator output from the rotor speed. Based on the definition of the current-speed characteristic, at a given speed of rotation, the generator cannot give more current than is limited by the current-speed characteristic. Consequently, the car generator operates in a short-circuit mode, and the current value is limited by the active and inductive resistance of the stator winding of the generator.

The higher the generator speed, the higher the inductive resistance of its stator winding. Therefore, the rate of rise of the current given by the generator, with an increase in the rotor speed and, accordingly, the inductive resistance of the stator winding decreases and the generator acquires the property of self-limiting current strength. Thus, an increase in the generator speed will not lead to combustion of the stator winding and its failure.

1. Automotive Generator Design

Modern claw-pole three-phase generator consists from the following nodes:

• stator, made in the form of a sheet steel package, with inserted into its grooves three-phase winding;
• rotor with claw poles, field winding and slip rings;
• rectifier unit;

• case-type brush holder with hinged voltage regulator;
• covers from the drive side and from the side of slip rings;
• pulley.

Generator stator consists of a stator package made of steel plates, each 0.5 mm or 1.0 mm thick. The plates are connected to each other along the outer surface by welding. The inner surface of the bag hastrapezoidalslots, evenly spaced around the circumference, in which the three-phase coil winding is laid. Each phase consists of six continuously wound coils. The stator is the armature of the synchronous generator.

Claw-shaped pole halves are usually made by cold stamping from strip steel with a thickness of about 12 mm, followed by annealing to improve the magnetic properties, since the structure of the inner layers of steel changes during stamping, which worsens the magnetization curve of the material. The sleeve and pole halves are clamped onto the rotor shaft using a press fit. The excitation winding is wound in rows on a plastic frame and fixed to the bushing. The field winding leads are soldered to copper slip rings, isolated from each other. On modern generators (compact generators), centrifugal fans are welded to the pole halves of the rotor on both sides, which suck in air from the ends of the generator and throw it out through the radial holes in the covers, cooling the frontal parts of the stator winding and rectifier block with voltage regulator.

Because the rotor of the generator rotates at high speed (up to 18000 rpm); to reduce vibration, the rotor is dynamically balanced. To do this, the rotor, after assembly, is checked on special equipment dynamically (during rotation) unbalance, i.e. how much the center of gravity of the rotor deviates from its axis. Permissible rotor unbalance 0.02 g m (0.02 grams per meter). To obtain the required imbalance, the rotor is balanced, i.e. by drilling holes in the pole halves, excess material is removed to bring the rotor center of gravity closer to its axis.

Installation the generator on the car is made by attaching it to lower bracket and bar fixed to the engine block. The tension of the generator drive belt is carried out by moving the generator around the axis of the lower bracket and tightening the fastening nut on the bar. The drive is carried out by a V-belt; gear ratio from 2 to 3. Belt tension is controlled by the amount of belt deflection under the action of the force applied to the belt.

In variants for cars, the nominal voltage is 14 V, and for trucks and buses in most cases, 28 V.

External factors affecting the generator:

• significant vibration with acceleration from 50g to 80g;
• high temperatures near the engine from 100 ° С to 120 ° С.
• corrosion caused by water, dirt, oils, salt;
• significant loads due to uneven speed of the engine crankshaft.

1. Generator current-speed characteristic

The main characteristic of a three-phase automobile generator is the current-speed characteristic at U = const. Three characteristic points are marked on it:

1. The switch-on point of the generator, operating at idle speed, it is at this speed that it reaches the rated voltage and begins to deliver current.

2. At the point of maximum current, the generator operates practically in short-circuit mode and delivers its maximum power. The maximum current depends solely on the reactance.

3. Design point. The generator utilization is at its maximum.

For valve (with a rectifier block) generators with self-limitation, the concept of rated power does not make sense. Therefore, the calculated (nominal) values ​​of power, current, speed are set according to the mode corresponding to the maximum value of the ratio of the rectified power to the speed of rotation.

The current-speed characteristic with a sufficient degree of accuracy is approximated by the equation

at, then the calculated values ​​can be determined if from the origin of coordinates spend tangent to the current-speed characteristic. The tangency point defines the calculated values,.

1. The principle of operation of the voltage regulator

The voltage regulator maintains the voltage in the vehicle's on-board network in given limits in all modes of operation when changing the rotational speed of the generator rotor, electrical load, ambient temperature. In addition, it can perform additional functions - to protect the generator elements from emergency modes and overload, to automatically include an excitation winding circuit or an alarm system for emergency operation of the generator into the on-board network.

All automotive voltage regulators work according to the same principle. Voltage The generator is determined by three factors - the rotor speed, the current delivered by the generator to the load, and the magnitude of the magnetic flux created by the field winding current. The higher the rotor speed and the lower the load on the generator, the higher the generator voltage. An increase in the current in the field winding increases the magnetic flux and, with it, the voltage of the generator; reducing the excitation current decreases the voltage. All voltage regulators stabilize the voltage by varying the excitation current. If the voltage rises or falls, the regulator will accordingly decrease or increase the excitation current and bring the voltage within the required limits.

Block diagram voltage regulator is shown in the figure.

1 - regulator; 2 - generator; 3 - comparison element;

4 - regulating element; 5 - measuring element

Block diagram of the voltage regulator

Regulator 1 contains measuring element 5, reference element 3 and regulatory Element 4. The measuring element senses the voltage of the generator 2 and converts it into a signal, which in the comparison element is compared with the reference voltage value.

If the value voltage differs from the reference value, a signal appears at the output of the measuring element, which activates the regulating element, which changes the current in the field winding so that the generator voltage returns to the specified limits.

In this way , the measuring circuit of the voltage regulator must be connected to the positive terminal of the generator or storage battery. If the functions of the regulator are expanded, then the number of its connections to the circuit increases, for example, for temperature compensation of the regulated voltage, it is connected to a temperature sensor built into the storage battery.

The input voltage divider is the sensitive element of electronic voltage regulators. From the input divider, the voltage goes to the comparison element, where the stabilization voltage of the zener diode usually plays the role of the reference value. The Zener diode (Zener diode) does not pass a current through itself at a voltage lower than the stabilization voltage and "breaks through", i.e. begins to pass a current through itself if the voltage on it will exceed the stabilization voltage. The voltage across the zener diode remains practically unchanged. The current through the zener diode turns on an electronic relay (transistor switch), which switches the excitation circuit in such a way that the current in the excitation winding changes in the desired direction. In vibration and contact-transistor controllers, the sensing element is presented in the form of an electromagnetic relay coil, the voltage to which, however, can also be supplied through the input divider, and the reference value is the tension force of the spring, which opposes the attraction force of the electromagnet. Switching in the field winding circuit is carried out by relay contacts or, in a contact-transistor controller, a semiconductor circuit controlled by these contacts. A feature of automobile voltage regulators is that they carry out discrete voltage regulation by turning the excitation winding on and off in the power circuit (in transistor controllers) or in series with the winding of an additional resistor (in vibration and contact-transistor controllers), while the relative duration of turning on the winding changes or an additional resistor.

Currently, electronic transistor regulators are used, it is convenient to consider the principle of operation of a voltage regulator using the example of a simple circuit.

Regulator 2 in the diagram works in conjunction with generator 1, which has an additional field winding rectifier. To understand the operation of the circuit, it should be remembered that, as shown above, the zener diode does not pass current through itself at voltages below the stabilization voltage. When the voltage reaches this value, the Zener diode breaks through and current begins to flow through it.

Transistors, on the other hand, pass current between the collector and emitter, i.e. open, if the current flows in the base-emitter circuit, and do not pass this current, i.e. closed if the base current is interrupted.

The voltage to the Zener diode VD1 is supplied from the output of the generator D through a voltage divider across the resistors R1, R2. While the generator voltage is low, and on the zener diode it is lower than the stabilization voltage, the zener diode is closed, the current through it, and, therefore, in the base circuit of the transistor VT1 does not flow, the transistor VT1 is closed. In this case, the current through the resistor R6 from the terminal D enters the base circuit of the transistor VT2, it opens, through its emitter-collector junction, current begins to flow in the base of the transistor VT3, which also opens. In this case, the excitation winding of the generator is connected to the power circuit through the emitter-collector transition VT3. The connection of transistors VT2, VT3, in which their collector leads are combined, and the base circuit of one transistor is powered from the emitter of the other, is called the Darlington circuit. With this connection, both transistors can be considered as one high gain composite transistor. Usually such a transistor is performed on a single silicon crystal. If the voltage of the generator has increased, for example, due to an increase in the frequency of rotation of its rotor, then the voltage on the Zener diode VD1 also increases.

When this voltage reaches the stabilization voltage, the Zener diode VD1 breaks through, the current through it begins to flow into the base circuit of the transistor VT1, which opens and with its emitter-collector transition shorts the base output of the composite transistor VT2, VT3 to ground. The composite transistor closes, breaking the field winding power supply circuit. The excitation current decreases, the generator voltage decreases, the Zener diode VD1, the transistor VT1 close, the composite transistor VT2, VT3 opens, the excitation winding is again included in the power circuit, the generator voltage increases, etc., the process is repeated.

1 - generator; 2 - regulator

Electronic transistor voltage regulator circuit

Thus, the voltage regulation of the generator by the regulator is performed discretely by changing the relative turn-on time of the excitation winding of the power circuit. In this case, the current in the field winding changes. If the speed generator has increased or its load has decreased, the turn-on time of the winding decreases, if the rotational speed has decreased or the load has increased, it increases.

The regulator circuit contains elements typical for the circuits of all voltage regulators used on cars. The diode VD2, when closing the composite transistor VT2, VT3, prevents dangerous voltage surges arising from an open circuit of the excitation winding with significant inductance.

In this case, the field winding current can be closed through this diode and dangerous voltage surges do not occur. Therefore, the VD2 diode is called a quenching diode. Resistance R3 is a hard feedback resistance. When the composite transistor VT2, VT3 is opened, it turns out to be connected in parallel with the resistance R2 of the voltage divider. In this case, the voltage at the Zener diode VD1 decreases sharply, which speeds up the switching of the regulator circuit and increases the frequency of this switching. This has a beneficial effect on the voltage quality of the generator set. Capacitor C1 is a kind of filter that protects the regulator from the influence of voltage pulses at its input.

In general, the capacitors in the regulator circuit either prevent the transition of this circuit to oscillatory mode and the possibility of outside influencehigh-frequencyinterference on the operation of the regulator, or accelerate the switching of transistors.

In the latter case, the capacitor, being charged at one moment in time, is discharged to basic the circuit of the transistor at a different moment, accelerating the switching of the transistor by the inrush of the discharge current and, consequently, reducing the power loss in it and its heating.

The addition of a resistor R to the generator set enhances the diagnostic capabilities of the HL lamp. In the presence of this resistor, if the field winding circuit is open while the car engine is running, the HL lamp will light up. The disadvantage of this solution is that a current flows through the resistor R, which heats the resistor, because of which its power must be sufficient to prevent overheating of the resistor. Continuous heating of resistor R also leads to unwanted heating of the adjacent dashboard components.

Voltage regulator design

t on and t off - respectively, the time of turning on and off the excitation winding of the generator; n 1 and n 2 - the frequency of rotation of the rotor of the generator, and n 2 is greater than n 1;

I B1 and I B2 - the average value of the current in the excitation winding

Change in current strength in the excitation winding I in time t

In the considered voltage regulator circuit, as in all regulators of a similar type, the switching frequency in the field winding circuit changes as the operating mode of the generator changes. The lower limit for this frequency is 25-50 Hz.

Currently, the voltage regulator circuit described above is used on previously developed cars and is being replaced by another type of electronic regulator circuits, in which the switching frequency is strictly set. Regulators of this type are equipped with a pulse width modulator (PWM), which provides a given switching frequency. The use of PWM reduces the influence on the operation of the regulator of external influences, for example, the level of ripple of the rectified voltage, etc.

At the same time, the rectifier unit of generating sets does not have additional diodes for powering the excitation winding and preventing the discharge of the battery when the car engine is not running. For the circuit to work in this case, a regulator of this type is connected to one of the phases of the generator stator winding. In regulators of this type, PWM, when the engine is not running, transfers the output transistor to an oscillatory mode, in which the current in the excitation winding is small and amounts to a fraction of an ampere. Therefore, the generator is not excited during engine start-up, which makes it possible to reduce the cranking resistance torque of the engine crankshaft and make it easier to start. After starting the engine, the signal from the generator phase output puts the regulator circuit in normal operation.

In this case, the regulator circuit also controls the lamp for monitoring the operating state of the generator set.

The presence of additional functions of the regulator in addition to the usual voltage regulation function (delay in the excitation of the generator at start-up, control control lamp or LED, etc.) allows you to call it multifunctional.

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The generator set is designed to power the car consumers with electric energy and charge the storage batteries when the engine is running. The composition of alternating current generator sets of modern cars includes, as a rule, a generator, a relay-regulator (voltage regulator) and switching equipment.

On vehicles of the KamAZ family, a generator set 3122.3771 with a built-in integral voltage regulator (type Y 120M) or a generator 6562.3701 with a voltage regulator 2712.3702 is installed.

Generating set 3122.3771 is a three-phase twelve-pole synchronous alternator with built-in rectifier unit, noise suppression capacitor, brush holder with voltage regulator.

The 3122.3771 generator is located in the upper front of the engine and is driven by two V-belts.

Technical characteristics of the generator 3122.3771

Rated voltage, V 28

Maximum recoil current, A 80

Rated power, W 2100

Adjustable voltage: max, V 27-28

min, B 28.8-30.2

The generator set has the following leads:

"+" - for connection with the storage battery and load;

"Ш" or "В" - for connection with the starter and instrument switch;

"W" or "~" - phase output for connection with a tachometer and starter blocking relay;

"+ D" or "D" - output from additional diodes for connection with a control lamp.

The generator set (Figure 14.8) consists of a stator 2, a rotor 5, a cover on the side of slip rings 8 with a rectifier unit and a brush holder with a voltage regulator 1, a cover on the drive side 7, pulley 4, fan 6.

1– brush holder with voltage regulator; 2 - stator; 3– bearing on the drive side; 4– pulley; 5 - rotor; 6 - fan; 7– cover on the drive side; 8 - cover from the side of slip rings; 9 - clamping screws

Figure 14.8 - Generating set:

The stator consists of a core and a winding. The core is made of electrical steel plates, varnished from each other and welded together along the outer surface of the package. Inside the core, 36 slots are evenly spaced around the circumference, designed to accommodate the windings.

The stator winding is three-phase, star-connected. The terminals of the phase windings are attached to the terminals of the rectifier device. The output of one of the phases "W" is used to connect the relay for blocking the starter and tachometer.

The rotor is an inductor and consists of a shaft, field winding, pole pieces, slip rings. The shaft is steel, on its corrugated surface a steel sleeve, pole pieces and slip rings are rigidly fixed by pressing. The pole pieces are made of mild steel and each have six pointed beaks that form six pairs of poles.

The field winding is wound on a steel sleeve. The winding is insulated from the sleeve and pole pieces with a polyethylene frame and cardboard washers. The ends of the field winding are soldered to the slip rings located on the insulating sleeve.

The cover on the side of the slip rings contains:

A rectifier unit with three additional diodes designed to power the excitation circuit is used for full-wave rectification of a three-phase current;

Plastic brush holder with voltage regulator, fixed on the cover with two screws, seasonal adjustment switch. The regulated voltage level of the generator in the "L" switch position (summer) should be within 27-28 V, in the "W" position (winter) - 28.8-30.2 V;

Noise suppression capacitor mounted on top of the cover;

Connecting block with output from additional diodes;

Phase output.

Closed ball bearings of the rotor shaft are installed in the generator covers. The fan and pulley are mounted on the generator shaft and secured with a nut and lock washer.

The generator is water resistant, so the vehicle can ford without damaging the generator. After leaving the water, the generator should remain operational.

The principle of the generator

When the instrument and starter switch is turned on, the voltage from the battery is supplied to the excitation winding (through the brushes and slip rings) located on the rotating part of the generator - the rotor. A magnetic field is created around the field winding, which, passing through the pole pieces, crosses the phase stator winding. As the rotor rotates, the magnetic field will also rotate. Since poles of different polarity alternately pass under each stator winding, the EMF induced in the stator windings will be variable, of the same frequency, but out of phase by 120 °.

The rectifier unit converts the alternating voltage into direct voltage, and when it becomes higher than the battery voltage, the generator will start feeding consumers and charging the battery. In this case, the excitation winding will be powered from the generator through additional diodes.

With an increase in the rotor speed, the voltage of the generator can reach a value that is dangerous for the receivers, therefore the generator works in conjunction with a voltage regulator that maintains the voltage in the vehicle's on-board network within specified limits.

The principle of operation of the voltage regulator

The generator voltage is determined by three factors - the magnitude of the magnetic flux created by the field winding current, the rotor speed and the current supplied by the generator to the load. The higher the rotor speed and the lower the load on the generator, the higher the generator voltage. An increase in the current in the excitation winding increases the magnetic flux and, with it, the generator voltage; reducing the excitation current decreases the voltage.

The voltage regulator stabilizes the voltage generated by the generator by varying the excitation current. If the voltage rises or falls, the regulator will accordingly decrease or increase the excitation current and bring the voltage within the desired limits.

The regulator contains a measuring element, a comparison element and a regulating element.

The measuring element of the electronic voltage regulator is a zener diode. The zener diode does not pass a current through itself at a voltage below the stabilization voltage and breaks through, that is, it starts to pass current if the voltage across it exceeds the stabilization voltage. The current through the zener diode turns on an electronic relay, which switches the excitation circuit in such a way that the current in the excitation winding changes in the desired direction. To match the stabilization voltage of the existing zener diodes with the voltage generated by the generator, an input voltage divider is used. From the input divider, the voltage of the multiple level of the on-board network voltage is fed to the zener diode.

The operation of the generator set of the KamAZ car

Figure 14.9 shows the wiring diagram for connecting the generator set to the electrical system.

Figure 14.9 - Electrical diagram of connecting the generator to the electrical equipment system

After turning on the instrument switch and starter (VPS), the terminals "AM" and "KZ" are closed to the first position. Electric current from the battery through a 60 A fuse, through the normally closed contacts of the excitation winding cut-off relay (ROOV), is fed to the “W” terminal of the generator, which is connected to the “B” terminal of the voltage regulator, which leads to the opening of the power transistor VT2 ( Figure 14.10). At the same time, electric current flows through the 8 A fuse into the relay coil of the battery switch ("ground") (RVM). Its contacts close, and electric current flows through the generator's initial excitation circuit: from the battery through a 60 A fuse, through the battery discharge indicator lamp (CL), which lights up, to the "+ D" terminal of the generator and then to the generator excitation winding, to the "Ш" terminal of the voltage regulator and through the open power transistor VT2 (Figure 14.10) to ground. Thus, the excitation winding of the generator is connected to the on-board network, and then the generator operates as described above (the principle of operation of the generator). After the generator began to generate electrical energy, the voltage at the "+ D" terminal of the generator becomes equal to the voltage at the "+" terminal of the generator, therefore, the current in the generator's initial excitation circuit disappears, and the control lamp goes out, and the excitation winding is powered from the block of additional diodes ... With an increase in the rotational speed of the rotor of the generator, the voltage regulator comes into operation.

Figure 14.10 - Electrical diagram of an integral regulator of the Y120M12I type

ROOV (relay for disconnecting the excitation winding) is designed to disconnect the excitation winding of the generator when using an electric torch device (EFU). The reason here is that the ESP plugs are designed for a voltage of 19 V, therefore, after starting the engine and operating it using the ESP, if the generator starts to generate electrical energy, the plugs will fail.

The ground switch (RVM) relay has two functions. The first is, after turning on the VPS, to break the circuit of the battery switch button in order to exclude the possibility of disconnecting the batteries from the on-board network when the engine is running (not shown in Figure 14.9). The second is to turn on the generator initial excitation circuit. This is done in order to unload the VPS contacts, since the current at the initial excitation of the generator can reach 5 A. On a KamAZ car, the instrument and starter switch switches only the RVM winding circuit and the voltage regulator control circuit, where the current is fractions of an ampere.

The control lamp performs a diagnostic function. After switching on the VPS, it lights up and signals the serviceability of the initial excitation circuit of the generator. After starting the engine, it should go out, if this did not happen, or the lamp came on while driving, the generator for some reason does not generate electrical energy.

Voltage regulator operation.

As noted above, when the VPS is turned on in the first position, the voltage is applied to the “B” terminal of the voltage regulator (Figure 14.10), and through the resistor R4, the current flows into the base circuit of the transistor VT2, which leads to its opening. In this case, the excitation winding of the generator is connected to the power circuit through the emitter-collector junction of the transistor VT2. The voltage to the composite Zener diode VD1 is supplied from the block of additional diodes of the generator through the "D" terminal of the voltage regulator and a voltage divider made on resistors R1, R2. While the generator voltage is low and at the zener diode it is lower than the stabilization voltage, the zener diode is closed, the current through it, and therefore in the base circuit of the transistor VT1 does not flow, the transistor VT1 is closed.

As the voltage at the “+” terminal of the generator increases, it increases at the output from the additional diode unit, and therefore on the voltage divider and the Zener diode VD1. When this voltage reaches the stabilization voltage, the Zener diode VD1 breaks through, the current through it begins to flow into the base circuit of the transistor VT1, which opens, and by its emitter-collector transition, the output of the base of the transistor VT2 is shorted to ground. Transistor VT2 closes, breaking the power circuit of the field winding. The excitation current decreases, the generator voltage decreases, the Zener diode VD1 and the transistor VT1 close, the transistor VT2 opens, the excitation winding is again included in the power circuit, the generator voltage increases, etc., the process is repeated.

Thus, the voltage regulation of the generator by the regulator is carried out discretely - by changing the relative time of turning on the excitation winding into the power circuit. If the rotational speed of the generator rotor has increased or its load has decreased, then the turn-on time of the excitation winding decreases, if the rotation frequency has decreased or the load has increased, it increases.

The diode VD2, when closing the transistor VT2, prevents dangerous voltage surges arising from the disconnection of the field winding circuit, which has significant inductance. In this case, the field current can be closed through this diode, and dangerous voltage surges do not occur. Therefore, the diode VD2 is called quenching. Resistance R3 is a feedback resistance. When the transistor VT2 opens, it turns out to be connected in parallel with the resistance R2 of the voltage divider. In this case, the voltage on the Zener diode VD2 decreases, which speeds up the switching of the regulator circuit and increases the frequency of this switching. Capacitor C1 is a filter that protects the regulator from the influence of voltage pulses at its input.

On the Ural car, the G-288E or 1702.3771 generators are installed together with the voltage regulator 2712.3702.

The composition of the generator set of the Ural car is similar to KamAZ, it differs in that the voltage regulator is located separately from the generator, and an ammeter is installed in the charging circuit.

Technical characteristics of the G 288E generator:

Rated voltage, V - 28

Load current maximum / rated, A - 40/36

Maximum power, W - 1100

The generator has a similar design, except that the voltage regulator is made separately, to reduce the ripple of the rectified voltage between the buses of the rectifier unit, a capacitor is built in and a tachometer and a starter blocking relay are connected to the "~" terminal.

A non-contact voltage regulator with three levels of adjustment is an electronic device based on semiconductor elements. The voltage is adjusted by switch 14 (Figure 14.11) located on the front cover of the regulator. The position of the switch lever corresponds to the voltages: maximum, average and minimum. The voltage level markings are located on the front cover of the regulator.

The voltage maintained by the regulator corresponds to 26.5 - 27.9 V - at the minimum level, 28.1 - 28.7 V at the average level, 28.7 - 30.1 V - at the maximum setting level.

Regulation of the voltage levels generated by the generator is carried out to prevent undercharging and overcharging of batteries, regardless of climatic conditions. If the ambient temperature is 0 ° C and below, it is necessary to move the switch lever to the "MAX" position. At a temperature of 0 ° C and above - to the "MIN" position to prevent the electrolyte from boiling away. If the batteries are undercharged or when the electrolyte has boiled out, set the lever to the "CP" position.

1 - fan; 2 - pulley; 3, 7 - ball bearings; 4 - rotor; 5 - brushes; 6 - brush holder cover; 8 - contact rings; 9 - rectifier unit; 10 - cover from the side of slip rings; 11 - stator; 12 - cover from the drive side; 13 - case; 14 - switch; 15, 16, 17 - terminals

Figure 14.11 - Generator G 288E and voltage regulator 2712.3702

The relay-regulator (Figure 14.12) is made on silicon transistors and works with the G 288E generator. The regulator has terminals "+" and "Ш", which are connected to the on-board network. The role of the negative terminal is played by the screw to which the negative wire is attached.

Figure 14.12 - Electrical schematic diagram of the generator set of the Ural 4320-31

In terms of circuit design, the voltage regulator is similar to that discussed earlier. The comparison element is the Zener diodes VD2, VD5, which control the amplifying transistor VT2, the power transistor VT1, the voltage divider includes R3, R6 -R8, the feedback resistor R2, the quenching diode VD1.

When the voltage of the generator is less than the regulated zener diodes VD2, VD5 are closed, the transistor VT2 is also closed, since its base is connected to the minus through the resistor R5. A positive potential is supplied to the base of the transistor VT1 through the resistor R1, the diodes VD3 and VD4, as a result of which the transistor VT1, opening, passes current into the excitation winding of the generator. The generator voltage increases.

When the generator voltage is higher than the regulated one, the Zener diode VD2, VD5 and the transistor VT2 open. In this case, the voltage at the base of the transistor VT1 decreases sharply, as a result of which the transistor closes, turning off the current of the excitation winding of the generator. The voltage of the generator decreases until the zener diode closes and the excitation current appears through the transistor VT1. The considered process is repeated, keeping the generator voltage constant regardless of the engine crankshaft speed.

The 6562.3701 generator of the KamAZ car together with the voltage regulator 2712.3702 works like a generator set on the Ural car.

The G 250P2 generator is installed on the UAZ-3151 car. Works in conjunction with the voltage regulator 2702.3702 (Figure 14.13).

Figure 14.13 - Electrical schematic diagram of the generator set of the UAZ-3151 car

The generator set of the UAZ car works in a similar way to the generator set Ural 4320-31. It differs in that the stator winding of the generator is made according to the "star" scheme, there is no capacitor in the rectifier unit and one zener diode is installed in the voltage regulator

Power supply system operating rules

When the vehicle is parked, it is necessary to disconnect the batteries from the electrical system.

Do not disconnect the batteries with the battery switch while the engine is running.

It is forbidden to press the button for turning on the electric torch device while the engine is running in order to avoid damage to the voltage regulator.

When carrying out electric welding work on the car, the storage batteries must be disconnected and the wires must be removed from the terminals "+" and "W" ("V") of the generator. The ground wire of the welding machine must be connected in the immediate vicinity of the weld.

The generator set is designed to provide power to the consumers included in the electrical equipment system and to charge the battery while the car engine is running. The output parameters of the generator must be such that in any modes of vehicle movement, a progressive discharge of the battery does not occur. In addition, the voltage in the vehicle's on-board network supplied by the generator set must be stable over a wide range of speed and load changes.

The generator set is a fairly reliable device that can withstand increased engine vibrations, high engine compartment temperatures, exposure to a damp environment, dirt and other factors.

Generator Specifications

Features of the device and principle of operation

Generator type 37.3701 - alternating current, three-phase, with built-in rectifier unit and electronic voltage regulator, clockwise rotation (from the drive side), with a fan at the drive pulley and ventilation windows in the end part. To protect against dirt, the back cover of the generator is covered with a protective cover.

The generator is based on the effect of electromagnetic induction. If a coil, for example, made of a copper wire, is penetrated by a magnetic flux, then when it changes, an alternating electric voltage appears at the terminals of the coil. Such coils, placed in the grooves of the magnetic circuit (iron package), represent the stator windings - the most important stationary part of the generator - they generate alternating electric current.
The magnetic flux in the generator is created by the rotor. It is also a coil (excitation winding) through which a direct current (excitation current) is passed. This winding is laid in the grooves of its magnetic circuit (pole system). The rotor - the most important moving part of the generator - also includes the shaft and slip rings. When the rotor rotates opposite the coils of the stator winding, the "north" and "south" poles of the rotor appear alternately, that is, the direction of the magnetic flux penetrating the stator windings changes, which causes an alternating voltage to appear in them.
A permanent magnet could be used as a rotor, but the creation of a magnetic flux by an electromagnet makes it easy to regulate the output voltage of the generator in wide ranges of rotation speeds and load current by changing the excitation current.

In order to obtain a constant voltage from an alternating voltage, six power semiconductor diodes are used, which make up a rectifier unit installed inside the generator case.

The power supply of the excitation winding is carried out from the generator itself and is supplied to it through the brushes and slip rings.
To ensure the initial excitation of the generator, after turning on the ignition, current is supplied to the "B" terminal of the voltage regulator through two circuits.

1. Battery positive - terminal 30 of the generator - contacts 30/1 and 15 of the ignition switch - contacts 86 and 85 of the ignition relay coil - minus the battery. The relay turned on, and the current went through the second circuit:
2. Battery positive - terminal 30 of the generator - terminals 30 and 87 of the ignition relay - fuse # 2 in the fuse box - terminal 4 of the white connector in the instrument cluster - 36 ohm resistor in the instrument cluster - battery charging indicator lamp - terminal 12 of the white connector in the instrument cluster - contact 61 - terminal "B" of the voltage regulator - excitation winding - terminal "W" of the voltage regulator - output transistor of the voltage regulator - minus the battery.

After starting the engine, the excitation winding is powered from the common terminal of three additional diodes installed on the rectifier unit, and the voltage in the car's electrical system is controlled by an LED or lamp in the instrument cluster. If the generator is working properly, after turning on the ignition, the LED or lamp should light up, and after starting the engine, it should go out. The voltage at the 30th contact and the common terminal 61 of the additional diodes becomes the same. Therefore, no current flows through the test lamp (LED), and it does not light up.
If the lamp (LED) lights up after starting the engine, then this means that the generator set is faulty, that is, it does not supply voltage at all, or it is lower than the battery voltage. In this case, the voltage at connector 61 is lower than the voltage at pin 30. Therefore, a current flows in the circuit between them, passing through the LED / lamp. He / she lights up to warn of a generator malfunction.

Voltage regulator: purpose and principle of operation

The generator set is equipped with a semiconductor electronic voltage regulator built into the generator. The voltage of a generator without a regulator depends on the rotation frequency of its rotor, the magnetic flux created by the excitation winding, and, therefore, on the current in this winding and on the amount of current given by the generator to consumers. The higher the rotational speed and the excitation current, the higher the generator voltage, the higher the current of its load, the lower this voltage.
The function of the voltage regulator is to stabilize the voltage when the speed and load change by controlling the excitation current.

Electronic controllers change the excitation current by turning the excitation winding on and off from the mains supply (additional diodes).
With an increase in the rotor speed, the generator voltage increases. When it begins to exceed the level of 13.5 ... 14.2 V, the output transistor in the voltage regulator is turned off, and the current through the field winding is interrupted. The generator voltage drops, the transistor in the regulator turns on and again passes current through the field winding.
The higher the rotational speed of the generator rotor, the longer the time of the locked state of the transistor in the regulator, therefore, the more the generator voltage decreases. This process of locking and unlocking the controller occurs at a high frequency. Therefore, voltage fluctuations at the generator output are invisible, and in practice it can be considered constant, maintained at a level of 13.5 ... 14.2 V.

Generator drive and fastening to the engine

The generator is driven from the crankshaft by a belt drive using a V-belt. Accordingly, for this belt, the generator drive pulley is made with one strand.
To cool the generator, plates are spot-welded on the back of the pulley. On the pulley, they are located almost perpendicularly and act as a fan.
The lower fastening of the generator to the engine is made on two fastening legs, mated to the engine bracket by one long bolt with a nut. Upper - through the pin to the tension bar.

Precautionary measures

The operation of a generating set requires compliance with some rules, mainly related to the presence of electronic components.

1. It is not allowed to operate the generating set with the battery disconnected. Even a short disconnection of the battery while the generator is running can lead to failure of the voltage regulator elements.
   When the battery is completely discharged, it is impossible to start the car, even if it is towed: the battery does not provide excitation current, and the voltage in the on-board network remains close to zero. The installation of a working charged battery helps, which then, when the engine is running, changes to the old, discharged one. In order to avoid the failure of the voltage regulator elements (and connected consumers) due to an increase in voltage, during the replacement of the batteries, it is necessary to turn on powerful consumers of electricity, such as heated rear window or headlights. In the future, for half an hour or an hour of engine operation at 1500-2000 rpm, the discharged battery (if it is in good working order) will be charged enough to start the engine.
2. It is not allowed to connect electricity sources of reverse polarity (plus on "ground") to the on-board network, which can occur, for example, when starting the engine from an external battery.
3. Any checks in the generator set circuit with the connection of overvoltage sources (above 14 V) are not allowed.
4. When carrying out electric welding work on a car, the "earth" terminal of the welding machine must be connected to the part to be welded. Disconnect the wires to the generator and voltage regulator.

Generator maintenance

Maintenance of the generator set is minimized and does not require any special knowledge and skills, this work can be performed by every motorist.
Start by cleaning the outside of the generator. Check the alternator-to-engine attachment, the reliability of the wiring to the alternator and voltage regulator, and the fan drive belt tension. If the tension is weak, then the generator works unstable, if it is strong, the belt and bearings wear out quickly.
Also check the condition of the drive belt. There should be no cracks or delamination on it.
The condition of the bearings can be checked by turning the alternator rotor by hand with the drive belt removed. In the normal condition of the bearings, the shaft should rotate smoothly, without jamming, strong backlash, noise and clicks.
In principle, these works can be limited to as long as no malfunctions appear.

Control check

Before leaving, it is recommended to check the operation of the generating set by the warning lamp installed on the instrument panel. After turning on the ignition before starting the engine, the control lamp is on, which allows you to check its operability. During normal generator set operation, the warning lamp goes out after engine start.
For a normally operating generator set, at medium engine speeds, the voltage should be in the range of 13.5 ... 14.2 V. The value of this voltage is measured with a voltmeter at the battery terminals.

Pre-repair diagnostics

A flashing battery charging warning lamp does not always indicate a malfunction inside the generator. Often the malfunction is trivial and lies on the surface. Therefore, you should not immediately climb into the generator and change the relay-regulator at breakneck speed, maybe it will help. Look at the preliminary diagnostics diagram. To carry it out, you may need a voltmeter with a scale of at least 15 V. Everyone can make these checks and, thereby, save themselves from unnecessary, incorrect actions and the loss of precious time.

If preliminary diagnostics showed that the field winding circuit is in good order, and the fault is in the generator, then after removing it, it is advisable to check all circuits, including the relay-regulator, according to the schemes described in section

Removal and installation of the generator

1. Disconnect the negative wire from the battery terminal (key 10).
2. Remove the plastic straps from the air intake pipe and the starter and alternator wiring harness.
3. Disconnect the generator field winding connector.
4. Unscrew the nut from the 30th terminal of the generator (key 10).
5. Unscrew the nut securing the alternator to the tensioning bar (key 17).
6. Use a spudger to move the generator to the engine and remove the drive belt.
7. Unscrew the three crankcase protection bolts (head 13) and remove it.
8. Remove the right engine mudguard by unscrewing the five 8-head self-tapping screws.
9. Unscrew the nut 19 from the lower bolt securing the generator to the bracket.
10. Remove the generator together with the air intake pipe. To do this, you need to tilt it slightly so that it goes down between the side member and the lower generator mounting bracket.
11. Install the generator in reverse order.

Disassembly and replacement of the voltage regulator

Begin preparation by cleaning the outside of the generator.

1. Remove the back cover together with the air inlet.
2. Disconnect the wire from the regulator relay, unscrew the two M4 screws and remove the regulator relay. To remove the old-style relay-regulator, unscrew the wire fixed under the extension terminal "30" of the generator. Insert a screwdriver blade between the control relay housing and the brush holder. Using a screwdriver as a lever, pull out the relay-regulator and pull out the brushes.
3. Blow out dust and dirt from the interior of the generator with compressed air using a compressor or pump.
4. If the rotor slip rings are severely burnt or worn, clean them with a fine abrasive paper.
5. Install the new relay-regulator in the reverse order of removal.

If, after the check, the old relay-regulator turns out to be in good order (the check method is described in the next section), then:

1. clean the contact connections of the generator and relay-regulator from dirt and oil with a cloth soaked in gasoline or solvent. Oil and dirt increase the resistance at the contact points, which reduces the generator's current output and increases brush wear.
2. check the minimum permissible protrusion of the brushes from the brush holder - 5 mm. If the brushes are jammed in the brush holder, replace the relay-regulator assembly. (For old-style control relays, it is sufficient to replace only the brush assembly.)
3. put it back in place.

Search and elimination of malfunctions of units and parts of the generator set

For troubleshooting the electrical circuits of the generating set, it is sufficient to have an ohmmeter. A more accurate check of the winding units requires the use of special devices, such as PDO-1, with its help, a fault finding in the windings is carried out by comparing their parameters. To test the relay-regulator, you will need constant voltage sources 12 ... 14 V and 16 ... 22 V. It is more convenient to carry out all checks on the generator removed from the car.

Checking the voltage regulator

Voltage regulators are not repaired, but replaced with new ones. However, before replacing it, it should be precisely established that it was he who failed.

Checking on a car

To check, you must have a DC voltmeter with a scale of up to 15 ... 30 volts.
With the engine running at medium speed and the headlights on, measure the voltage at the battery terminals. It should be in the range of 13.5 ... 14.2 V.
In the event that a systematic undercharging or overcharging of the battery is observed and the regulated voltage does not fit within the specified limits, it is possible that the voltage regulator is faulty and must be replaced. In order to find out if the regulator is in good working order or not, let's check it according to the figure shown below.

Checking the removed regulator

The regulator removed from the generator is checked according to the following schemes (old model on the left, new one on the right):

It is better to check the relay-regulator assembled with a brush holder, since in this case you can immediately detect breaks in the leads of the brushes and poor contact between the leads of the voltage regulator and the brush holder.
Switch on the lamp 1 ... 3 W, 12 V. Between the brushes, connect the power supply to the terminals "B", "C" and to the mass of the regulator, first with a voltage of 12 ... 14 V, and then with a voltage of 16 ... 22 V.
If the regulator is working properly, then in the first case the lamp should be on, and in the second it should go out.
If the lamp is on in both cases, then there is a breakdown in the regulator, and if it does not light up in both cases, then there is an open circuit in the regulator or there is no contact between the brushes and the terminals of the voltage regulator.

Checking the rotor winding (excitation)

To check the winding, you should turn on the ohmmeter to measure the resistance and bring its leads to the rotor rings. In a working rotor, the winding resistance should be in the range of 1.8 ... 5 ohms. If the ohmmeter shows infinitely high resistance, this means that the field winding circuit is broken.
The rupture most often occurs at the place where the winding leads are soldered to the rings. The quality of this soldering should be checked carefully. The check can be carried out with a needle, moving the winding leads in the place of their soldering. Burning out of the winding is evidenced by the darkening and crumbling of its insulation, which can be detected visually. Burning out the windings leads to an open or to turn-to-turn short circuit in the winding with a decrease in its total resistance. Partial turn-to-turn closure, in which the resistance of the winding changes little, can be detected by the PDO-1 device, by comparing this winding with a known good one. After checking the resistance of the winding, check that it has no short circuit to ground. To do this, one lead of the ohmmeter is brought to any ring of the rotor, and the other to its beak. For a working winding, an ohmmeter will show infinitely high resistance. A defective rotor must be replaced.

Checking the stator winding

The stator is checked separately after disassembling the generator. Its winding leads must be disconnected from the rectifier valves.

First of all, check with an ohmmeter for any breaks in the stator winding (a). Then, by connecting the ends of the ohmmeter to one of the winding leads and an uninsulated section of the stator iron, check if its turns are closed to "mass" (b). The ohmmeter should show an open circuit in a working winding. Checking the turn-to-turn circuit in the stator windings can be carried out with sufficient accuracy using the PDO-1 device. The break can also be checked with an ohmmeter, connecting it to the zero point and alternately to the output of each phase. An external examination should make sure that there is no cracking of the insulation and burning of the winding, which occurs during a short circuit in the valves of the rectifier unit. Replace the stator with such a damaged winding.

Checking the valves (diodes) of the rectifier unit

The diodes of the rectifier unit are checked after disconnecting it from the stator winding with an ohmmeter. A working valve passes current only in one direction. Defective - it can either not pass current at all (open circuit), or pass current in both directions (short circuit). If one of the rectifier valves is damaged, the entire rectifier unit must be replaced.
The short circuit of the rectifier unit valves can be checked without disassembling the generator, but only by removing the protective cover. Also, the terminal "B" of the regulator is disconnected from the terminal "30" of the generator and the wire from the terminal "B" of the voltage regulator. You can check with an ohmmeter or using a lamp (1 ... 5 W, 12 V) and a battery.
In order to simplify the fastening of the rectifier parts, three valves (with a red mark) create a "plus" of the rectified voltage on the body. These valves are "positive" and they are pressed into one plate of the rectifier unit, connected to the terminal "30" of the generator. The other three valves ("negative" with a black mark) have a "minus" rectified voltage on the body. They are pressed into another plate of the rectifier unit, connected to ground.
First check if there is a short in both the "positive" and "negative" valves at the same time. To do this, connect the "plus" of the battery through the lamp to the terminal "30" of the generator, and the "minus" to the generator case:

If the lamp is on, the "negative" and "positive" valves are short-circuited.
A short circuit of the "negative" valves can be checked by connecting the "plus" of the battery through a lamp with one of the rectifier unit mounting bolts, and "minus" with the generator case:

If a lamp is lit, it means a short circuit in one or more "negative" valves. It should be remembered that in this case, the burning of the lamp may also be a consequence of the closure of the turns of the stator winding to the generator case. However, such a malfunction is less common than short-circuiting of valves.
To check for a short circuit in the "positive" gates "plus" of the battery through the lamp, connect it to terminal 30 of the generator, and "minus" to one of the bolts of the rectifier unit:

If the lamp is on, it will indicate a short circuit in one or more of the "positive" valves.
A break in the valves without disassembling the generator can be detected either with an oscilloscope or when checking the generator at the stand for a significant decrease (by 20-30%) in the value of the supplied current compared to the nominal one. If the windings, additional diodes and the voltage regulator of the generator are in good order, and there is no short circuit in the valves, then the reason for the decrease in the output current is an open in the valves.

Checking additional diodes

A short circuit of additional diodes can be checked according to the diagram:

Connect the "plus" of the battery through the lamp (1 ... 3 W, 12 V) to the terminal "61" of the generator, and the "minus" to one of the bolts of the rectifier unit.
If the lamp lights up, then there is a short circuit in one of the additional diodes. You can find a damaged diode only by removing the rectifier unit and checking each diode separately.
An open circuit in the additional diodes can be detected by an oscilloscope by the distortion of the voltage curve at the "61" plug, as well as by the low voltage (below 14 V) at the "61" plug at an average generator rotor speed.

Condenser test

The capacitor serves to protect the electronic equipment of the car from voltage pulses to the ignition system, as well as to reduce interference with radio reception.
Damage to the capacitor or loosening of its attachment to the generator (deterioration of contact with ground) is detected by an increase in radio interference when the engine is running.
Roughly, the performance of the capacitor can be checked with a megohmmeter or a tester (on a scale of 1 ... 10 MΩ). If there is no break in the capacitor, then at the moment of connecting the probes of the device to the terminals of the capacitor, the arrow should deviate in the direction of decreasing resistance, and then gradually return back.
The capacitance of the capacitor, measured with a special device, should be 2.2 μF + 20%.

Checking and replacing bearings

Begin checking the bearings with an external inspection, detecting cracks in the cages, enveloping or chipping of metal, the presence of corrosion, etc. Check the ease of rotation and the absence of strong play and noise. If the bearing is badly worn out or damaged, it must be replaced.
The procedure for replacing bearings (the generator is removed from the car).

1. Remove the back cover together with the air intake pipe.
2. Remove the voltage regulator.
3. Unscrew the alternator pulley and pull out the key.
4. Unscrew the 4 nuts of the tie bolts and remove the front cover of the generator together with the rotor and bearings.
5. Remove the defective bearing from the drive end cover. Unscrew the nuts of the screws tightening the bearing retaining washers, remove the washers with screws and press out the bearing using a hand press. If the screw nuts do not loosen (screw ends are bent), cut off the screw ends.
6. Press in a new bearing. To do this, put the new bearing on the seat, and on top of it - the old one. With light hammer blows on the old bearing, push the new bearing into the seat. If the bearing runs too tight, spray the outer ring with WD-40 fluid.
7. Using a puller, press off the second bearing on the back of the rotor.
8. Press in a new bearing (see item 6).
9. Reassemble in reverse order.

Checking the covers

An external examination determines the absence of cracks passing through the bearing seat, breakage of the generator mounting legs, severe damage to the seats. If there is such damage, the cover must be replaced. If severe wear of the bearing seats is detected, replace the covers.

Finding generator malfunctions according to diagrams

Typical generator malfunctions

Causes of malfunction	Remedy
The LED (lamp) of the voltmeter does not light up when the ignition is turned on. Control devices do not work
1. The LED (lamp) of the voltmeter is damaged	Replace the LED (lamp) of the voltmeter
2. Blown fuse # 2 in the fuse box	Replace fuse
3. Open in the power supply circuit of the instrument cluster:
no voltage is supplied from plug "B" of the fuse box to the instrument cluster	check the "O" wire and its connections from the fuse box to the instrument cluster
no voltage is supplied from the ignition relay to plug "B" of the fuse box	check the "RG" wire and its connections from the fuse box to the ignition relay
open or broken contact in the wire connecting to the "mass" of the instrument cluster	check the wire "CH" and its connections from the instrument cluster to ground
4. The ignition switch or relay does not work:
faulty contact part or ignition relay	check, replace the contact part of the switch or ignition relay
no voltage is supplied from the switch to the ignition relay	check the wire "Ch" and its connections between the switch and the ignition relay
open or broken contact in the wire connecting to the "ground" of the ignition relay	check the "Ч" wire and its connections from the ignition relay to ground
5. Damaged voltage stabilizer in the instrument cluster	Replace voltage regulator
When the ignition is turned on and after starting the engine, the LED / voltmeter lamp does not light up, the battery is discharged
The generator excitation winding circuit is faulty:
1. Fuse No. 2 is blown	Replace fuse
2. Broken wires in the circuits: fuse # 2 - instrument cluster; instrument cluster - relay-regulator.	Find and fix the break
3. In the dashboard; burned out LED / lamp; breakage of printed conductors; faulty damping resistance or poor soldering of its terminals	Replace LED / lamp; eliminate the open circuit of the printed conductors; replace or solder resistance.
4. There is no "ground" between the case and the relay-regulator	Clean oxides and dirt from the junction of the relay-regulator with the generator
5. Defective relay-regulator	Replace regulator relay
6. Broken rotor winding	Replace rotor
The voltmeter LED is on when the engine is running. Battery discharged
1. Slipping of the alternator drive belt	Adjust the belt tension
2. There is no contact between the terminals "B" and "W" of the voltage regulator and the terminals of the brushes	Strip the terminals "B" and "W" of the voltage regulator and brushes, bend the leads of the regulator
3. Open circuit between the instrument cluster and the generator plug "61"	Check the "KB" wire and its connections from the generator to the instrument cluster
4. Wear or hanging of brushes, oxidation of slip rings	Replace the brush holder with brushes, wipe the rings with a cloth soaked in gasoline
5. Damaged voltage regulator	Replace voltage regulator
6. The valves of the rectifier unit are damaged.	Replace rectifier unit
7. Damaged power supply diodes of the field winding	Replace diodes or rectifier unit
8. Unsoldering the leads of the excitation winding from the slip rings	Solder the leads or replace the alternator rotor
9. Open or short circuit in the stator winding, short circuit to ground	Replace generator stator
The battery is discharged during operation, but there are no external signs of abnormal generator operation
1. Defective battery: oxidation of wires or battery terminals; not enough electrolyte; closure of one or more cans	Clean the wires / terminals; top up with distilled water, replace the battery
2. Dirt, oiling, oxidation of the slip rings of the rotor	Clean slip rings with a cloth soaked in gasoline, fine sandpaper
3. Dirt, oiling of the brushes of the relay-regulator or poor contact due to their excessive wear	Clean the brushes from dirt with a cloth soaked in gasoline. Replace the relay-regulator assembly. (For relay-regulators of the old model, it is enough to replace only the brushes)
4. Excessive energy consumption by powerful / additional consumers	Replace the generator with another, more powerful one (VAZ-2108 - 955.3701; GAZ-3102)
5. Turn-to-turn short circuit or breakage of one of the phases of the stator winding	Replace stator winding
The voltmeter LED flashes when the engine is running. The battery is being recharged
Damaged voltage regulator (short circuit between terminal "Ш" and "ground")	Replace voltage regulator
The control lamp lights up at full heat when the engine is running
Additional and / or rectifier diodes are faulty	Replace diodes or rectifier assembly
Increased generator noise
1. Loose generator pulley nut	Tighten the nut
2. Damaged rotor bearings or their seats	Replace bearings, generator cover / covers
3. Turn-to-turn short circuit or short to "ground" of the stator winding (howl of the generator)	Replace stator
4. Short circuit in one of the generator valves	Replace rectifier unit
5. Creak of brushes	Wipe the brushes and slip rings with a cotton cloth soaked in gasoline
6. Grazing the rotor by the stator poles	Replace rotor, stator. Pay attention to bearings
Rapid wear of brushes and slip rings
1. Ingress of oil or dirt on slip rings	Clean the slip rings with a cloth soaked in gasoline, fine sandpaper
2. Increased runout of slip rings	Replace rotor

Attention! The "minus" of the storage battery must always be connected to ground, and the "plus" - is connected to the terminal "30" of the generator. An erroneous re-insertion of the battery will immediately cause an increased current through the generator valves and they will fail.

It is not allowed to operate the generator with a disconnected battery. This will cause short-term overvoltages at terminal "30" of the generator, which can damage the generator voltage regulator and electronic devices in the vehicle's on-board network.

It is forbidden to check the generator's performance "for a spark" even by short-term connection of the "30" clamp of the generator to "ground". In this case, a significant current flows through the valves, and they are damaged. The generator can only be checked with an ammeter or voltmeter.

It is not allowed to check the generator valves with a voltage of more than 12 V or with a megger, since it has a voltage that is too high for the valves and they will be broken during testing (a short circuit will occur).

It is forbidden to check the electrical wiring of the car with a megometer or a lamp supplied with a voltage of more than 12 V. If such a check is necessary, then first disconnect the wires from the generator.

Check the insulation resistance of the generator stator winding with increased voltage only on the bench and always with the phase winding leads disconnected from the valves.

When electric welding of units and parts of the car body, disconnect the wires from all terminals of the generator and the terminals of the battery.

Malfunctions of a car's electrical equipment are very common and occupy one of the leading places in the list of breakdowns. They can be conditionally divided into faults of current sources (batteries, generators) and faults of consumers (optics, ignition, climate, etc.). The main the car's power supplies are batteries and generators... Failure of each of them leads to a general malfunction of the car and its operation in abnormal modes, or even to immobilization of the car.

In the electrical equipment of a car, the battery and generator work in an inseparable tandem. If one fails, the other will fail after a while. For example, it leads to an increase in the charging current of the generator. And this entails a malfunction of the rectifier (diode bridge). In turn, when supplied from the generator, the charging current may increase, which will inevitably lead to systematic recharging of the battery, "boiling away" of the electrolyte and rapid destruction.

Common generator malfunctions:

• wear or damage to the pulley;
• wear of current-collecting brushes;
• collector wear (slip rings);
• damage to the voltage regulator;
• closure of the turns of the stator winding;
• wear or destruction of the bearing;
• damage to the rectifier (diode bridge);
• damage to the charging circuit wires.

Common battery malfunctions:

• short circuit of the electrodes / plates of the battery;
• mechanical or chemical damage to the battery plates;
• violation of the tightness of the battery cans - cracks in the battery case as a result of impacts or improper installation;
• chemical. The main reasons for these malfunctions are:
• gross violations of operating rules;
• expiration of the product's service life;
• various manufacturing defects.

Of course, the design of a generator is more complex than a storage battery. It is quite reasonable that there are many times more generator malfunctions, and their diagnosis is much more difficult.

It is very useful for a motorist to know the main causes of generator malfunctions, ways to eliminate them, as well as preventive measures to prevent breakdowns.

All generators are subdivided into generators alternating and direct current... Modern light vehicles are equipped with alternators with a built-in diode bridge (rectifier). The latter is necessary for converting current into direct current, on which the car's electrical consumers work. The rectifier, as a rule, is located in the cover or housing of the generator and is one piece with the latter.

All electrical appliances of the car are designed for a strictly defined range of operating voltage currents. As a rule, operating voltages are in the range of 13.8-14.7 V. Due to the fact that the generator is "tied" by a belt to the engine crankshaft, from different revolutions and vehicle speed, it will work differently... It is for smoothing and regulating the output current that the voltage regulator relay is intended, which plays the role of a stabilizer and prevents both surges and dips of the operating voltage. Modern generators are equipped with built-in integrated voltage regulators, colloquially referred to as "chocolate" or "pill".

It is already clear that any generator is a rather complex unit, extremely important for any car.

Types of generator faults

Due to the fact that any generator is an electromechanical device, respectively, there will be two types of malfunctions - mechanical and electrical.

The first include the destruction of fasteners, housing, malfunction of bearings, hold-down springs, belt drive and others not related to the electrical part of the breakdown.

Electrical faults include winding breaks, diode bridge faults, brush burnout / wear, turn-to-turn short circuits, breakdowns, rotor beatings, and relay-regulator faults.

Often, symptoms that are characteristic of a faulty generator may appear due to completely different problems. As an example, a poor contact in the fuse socket of the generator field winding circuit will indicate a malfunction of the generator. The same suspicion may arise due to burnt contacts in the ignition switch housing. Also, the constant burning of the generator malfunction indicator lamp can be caused by a breakdown of the relay, the blinking of this switching lamp may indicate a generator malfunction.

The main symptoms of a malfunctioning generator:

• When the engine is running, the indicator lamp for battery discharge flashes (or is continuously on).
• Discharge or recharge (boil-off) of the battery.
• Dim car headlights, rattling or low beeps when the engine is running.
• Significant change in the brightness of the headlights with an increase in the number of revolutions. This can be permissible when increasing the speed (overglowing) from the idle mode, but the headlights, having lit up brightly, should not increase their brightness further, remaining at the same intensity.
• Extraneous sounds (howl, squeak) emanating from the generator.

The tension and general condition of the drive belt should be checked regularly. If cracks or delamination occur, replace immediately.

Alternator repair kits

To eliminate the indicated malfunctions of the generator, it will be necessary to carry out repairs. When you start looking for a generator repair kit on the Internet, prepare yourself to be disappointed - the kits offered usually contain washers, bolts and nuts. And sometimes it is possible to return the generator to working capacity only by replacing - brushes, diode bridge, regulator ... Therefore, a brave man who decides to repair makes an individual repair kit from those parts that fit his generator. It looks something like the table below, using the example of a pair of generators for the VAZ 2110 and Ford Focus 2.

Generator VAZ 2110 - KZATE 9402.3701-03 for 80 A. It is used on VAZ 2110-2112 and their modifications after 05.2004, as well as on VAZ-2170 Lada-Priora and modifications

Generator Renault Logan - Bosch 0 986 041 850 at 98 A. Applies to Renault: Megane, Scenic, Laguna, Sandero, Clio, Grand Scenic, Kangoo, as well as Dacia: Logan.

Troubleshooting

On modern cars, using the "old-fashioned" method by throwing off the battery terminal can lead to serious damage to many of the electronic systems of the car. Significant voltage drops in the vehicle's on-board network can damage almost all on-board electronics. That is why modern generators are always checked only by measuring the voltage in the network or diagnosing the removed unit itself at a special stand. First, the voltage at the battery terminals is measured, the engine is started and readings are taken while the engine is running. Before starting, the voltage should be about 12 V, after starting - from 13.8 to 14.7 V. A deviation to a large side indicates that you are "overcharging", which implies a malfunction of the relay-regulator, to a smaller one - that no current is supplied. The lack of recharging current indicates generator malfunctions or chains.

Causes of breakdowns

Common causes of generator malfunctions- this is trivial wear and tear. Almost all mechanical failures, be it brush wear or broken bearings, are the result of long service life. Modern generators are equipped with sealed (maintenance-free) bearings that simply need to be replaced after a certain period or vehicle mileage. The same applies to the electrical part - often the entire assemblies must be replaced.

Also, the reasons may be:

• poor quality of manufacturing of components;
• violation of operating rules or work outside the limits of normal modes;
• external factors (salt, liquids, high temperature, road "chemicals", dirt).

Generator self check

The easiest way is to check the fuse. If it is serviceable and its location. Check the free rotation of the rotor, the integrity of the belt, wires, housing. If nothing aroused suspicion, the brushes and slip rings are checked. In the process of operation, the brushes inevitably wear out, they can get jammed, skewed, and the grooves of the slip rings become clogged with graphite dust. A clear sign of this is excessive sparking.

Cases of complete wear or breakdown of both bearings and stator breakdown are not uncommon.

The most common mechanical generator problem is bearing wear. A symptom of this malfunction is a howl or whistle when the unit is operating. Of course, the bearings must be replaced immediately after inspecting the seats. Attenuation can also cause poor generator performance. One of the signs may be a high-pitched whistle from under the hood when the car accelerates or accelerates.

To check the rotor field winding for short-circuited turns or breaks, you need to connect a multimeter, switched to resistance measurement mode, to both slip rings of the generator. Normal resistance is 1.8 to 5 ohms. The reading below indicates the presence of a short circuit in the turns; above - a straight winding break.

To check the stator winding for "breakdown to ground", they must be disconnected from the rectifier unit. With the resistance readings given by the multimeter, which are of infinite value, there is no doubt about the absence of contact between the stator windings and the case ("ground").

A multimeter is used to check the diodes in the rectifier unit (after completely disconnecting from the stator windings). Test mode - "diode test". The positive probe is connected to the positive or negative of the rectifier, and the negative to the phase terminal. After that, the probes are swapped. If, at the same time, the values ​​of the multimeter readings are very different from the previous ones, the diode is good, if they do not differ, it is faulty. Another sign indicating the imminent "demise" of the diode bridge of the generator is the oxidation of the contacts, and the reason for this is the overheating of the radiator.

Repair and troubleshooting

Everything mechanical problems are eliminated by replacing faulty assemblies and parts(brushes, belt, bearings, etc.) for new or serviceable ones. On older generators, slip ring grooving is often required. Drive belts change due to wear, maximum elongation or expiration. Damaged rotor or stator windings, they are currently being replaced with new assembled ones. Rewinding, although it is found among the services of auto repairmen, is less and less often - it is expensive and impractical.

And that's all electrical problems with a generator you need decide due to verification like others chain elements(in particular the battery), so and directly its details and output voltage. One of the frequent problems that car owners have to face is overcharge, or vice versa, generator low voltage... Checking and replacing the voltage regulator or diode bridge will help to eliminate the first malfunction, and it will be a little more difficult to figure out the low voltage output. There can be several reasons why the generator produces a low voltage:

1. increased load on the on-board network by consumers;
2. breakdown of one of the diodes on the diode bridge;
3. failure of the voltage regulator;
4. slippage of the V-ribbed belt (due to weak tension)
5. poor contact of the ground wire on the generator;
6. short circuit;
7. a drained battery.

A generator set is a technical device that is an independent source of electrical energy obtained by burning liquid and gaseous fuels in diesel engines, internal combustion engines and gas turbine plants.

What it is

The generator set consists of an electric generator, the shaft of which is connected to the shaft of the engine, which runs on the appropriate type of fuel (gas, petrol, diesel).

Schematically, a generator set running on gasoline or diesel fuel can be depicted as follows:

Kinds

Generating sets differ in their design and configuration, installation method and power, as well as other technical characteristics.

According to the installation method, these are:

• Stationary installed - serve as the main or backup source of electrical energy for objects of various types (industry, housing and communal services, agriculture, etc.). The power of such devices is from 5.0 to several hundred kW.
• Mobile (mobile) - mounted on a special chassis (platform) and can serve as the main and backup source of energy for small energy consumption facilities, as well as in the elimination of emergencies in places where there are no stationary electrical networks. The power of installations in this group of installations is from 2.0 to 18.0 kW.
• Portable - These are portable devices used to supply power to a small electrical load. They are used as an emergency or reserve source of energy, power - from 0.5 to 5.0 kW.

Based on the type of fuel used, generating sets are classified as:

• Diesel - when diesel is used. As a rule, these are permanently installed installations, less often - mobile ones. The power of a group of generating sets of this type can reach 200 - 300 kW.
• Gasoline - run on low octane gasoline. On mobile units, four-stroke engines are mounted, on portable ones, as a rule, two-stroke ones. The power of this group is up to 18.0 kW.
• Gas - run on gas, when burned, the gas-piston engine transfers the rotation of its shaft to the shaft of an electric generator that generates an electric current.

These are permanently installed installations that serve as the main source of electrical energy, but can also be used as a backup, if necessary.

By the type of generator used, the installations are subdivided into:

• With an asynchronous electric generator - they have a low cost, but low technical performance. They are installed in low-power plants, usually of a portable or mobile type.
• With a synchronous electric generator - they are able to withstand peak overloads in the electrical networks connected to them, with a high quality of the generated voltage. Installed on powerful diesel generating stations.

Diesel power station

A diesel power plant is a generator set that is equipped with a diesel engine.

The composition of the equipment included in the diesel power plant kit is shown in the following figure:

1 - diesel engine;

2 - electric alternator;

3 - base, frame or frame on which all elements of the power plant are attached;

4 - electrical cabinet, which is a power plant control and protection unit;
5 - tank for storing diesel fuel;

6 - storage battery for starting the diesel engine into operation;

7 - cooling unit, consisting of a radiator and a fan. In the radiator, the circulating fluid is cooled by the fan of the shaft-mounted main diesel engine.

8 - exhaust pipe, which provides exhaust gases removal;

9 - clutch providing connection between the engine shaft and the electric generator shaft.

For different models of diesel power plants, the engine can be started in a different way than in the diagram below. For these purposes, a starting motor ("launcher") running on gasoline or a kick-starter driven by the operating personnel can be used.

The couplings that connect the engine shaft to the generator shaft must have a high damping capacity, be collapsible and elastic with non-metallic elements for connecting the half couplings (with a rubber sprocket, with an intermediate disc, a toroidal shell).

Main technical characteristics

The main, general technical characteristics that determine the parameters of operation and the possibility of using diesel power plants are:

• The electrical power delivered by the generator is measured in kW;
• Shaft speed, measured in revolutions per minute;
• Electrical power factor (cos φ);
• The number of phases generated by the electric current;
• Voltage generated by current (220/380 V);
• The frequency of the generated current (50 Hz);
• Fuel consumption per hour of work;
• Fuel tank volume;
• Weight;
• Dimensions.

In addition to general technical characteristics, the power plant passport contains technical characteristics of a diesel engine and an electric generator, which are, for:

• Engine:
• Engine model;
• Manufacturing company;
• The number of cylinders and their location;
• Cylinder diameter, measured in mm;
• Piston stroke, measured in mm;
• Cooling system type;
• Rated speed of the motor shaft;
• Rated power at rated engine speed;
• Specific fuel consumption, measured in g / kW * hour;
• Engine weight.
• Generator model;
• Manufacturing company;
• Rated voltage at the generator output terminals;
• Efficiency at full load;
• Power factor (cos φ);
• Rated shaft speed;
• Apparent electrical power, measured in kVA;
• Generator weight.

In order for a diesel power plant, which is a complex technical device, to work for a long time and not cause trouble for users, it is necessary to carry out its maintenance on time.

Maintenance can be classified as:

• Daily routine inspections are carried out before the power plant is put into operation.
• Periodic preventive inspections are carried out in accordance with an individual schedule determined for each specific model of a diesel power plant.
• Technical work, the frequency of which depends on the operating hours of the installation and in accordance with the schedule for their implementation.

During daily inspections or, during the cyclical operation of the power plant, at its start-up, the following is performed:

• Checking the integrity of components and assemblies;
• Checking oil and coolant levels;
• Checking the oil pressure in the engine lubrication system.

During periodic inspections, the following is performed:

• Checking and eliminating malfunctions of units and systems that ensure the operation of a diesel engine. Adjust them if necessary.
• Testing the operation of the electric generator, if necessary - adjusting.
• Checking the insulation resistance of electrical wires and other elements of electrical circuits.
• Checking the performance of electrical devices of the protection system, automation and start-up of power units.

When performing routine maintenance, the work specified by the manufacturer of the installation is performed for each specific type of service (TO1, TO2, etc.).

Maintenance is carried out on the basis of its implementation schedules and in accordance with the list of works to be performed.

Each maintenance of the power plant corresponds to a certain number of hours worked by it.

In a cyclical operation of diesel power plants, it is necessary to carry out periodic testing of their operation, which should be performed at least once a month.

Any technical device has its own advantages and disadvantages, this fully applies to diesel power plants.

So, the advantages of using installations of this type include:

1. Significant electrical power in comparison with gasoline counterparts.
2. The ability to stabilize the generated voltage, thereby ensuring its quality indicators, regardless of peak loads when starting electric motors and other electrical devices.
3. High efficiency.
4. Ability to work in a continuous cycle for a long time without compromising performance.
5. Relatively low noise level when generating electrical energy.
6. Ability to work in a wide temperature range of ambient air.
7. Maintainability and relatively low maintenance costs.

1. Large mass of installations and significant overall dimensions.
2. For the installation of high-power models, a special base (frame) or foundation is required to ensure the strength of the fastening of the structural elements and their further safe operation.
3. The need to monitor the quality of the fuel used, depending on the season (ambient temperature).
4. With an incomplete load (below 40.0%), there is a significant wear of units and mechanisms, which leads to the need to perform additional maintenance and, as a result, to financial costs.
5. High installation cost.