Auxiliary contacts in electrical engineering - normally open and closed or make and break, respectively
Definitions
Auxiliary contacts- contacts of switching devices operating with auxiliary circuits, which are not electrically connected with the main circuit and the control circuit. Auxiliary contacts are kinematically connected with the main ones and reflect their switching position (closed or open).
Main circuit- the electrical system that the machine closes and opens. Control circuit- the electrical system by which the device changes the switching position.
Types of auxiliary contacts
NO contact- a contact that is closed when the main contacts are brought together and open when the main contacts are separated (corresponding to the current position of the main contacts). That is, in the off position, the closing contact does not pass electric current.
Break contact- a contact that is open when the main contacts are brought together and closed when the main contacts are separated (reverse correspondence). When the device is on, no electric current flows.
Such contact groups are used on red stop buttons. When the stop button is pressed, the control circuit is interrupted and the engine stops.
Corresponds to definitions 2.3.13 and 2.3.14 of the normative document GOST 50030 part 1.
Compliance and designation
Contact Matching:
- N.O. = normally open = normally open = n ormal o pen;
- N/C = Normally closed = Normally closed = n normal c lost.
Considering the first and last statements, stand for:
- 1z \u003d 1NO;
- 1p = 1NC.
The number means the amount auxiliary contacts. hence the markings:
- two pieces - 2z \u003d 2NO;
- three pieces - 3p = 3NC;
- four pieces - 4z \u003d 4NO;
- two closing and two breaking - 2з+2р = 2NO+2NC.
Take the sign "=" as a union "or".
Additional Information: types of contact elements and their designation according to GOST 50030 part 5.1.
Photo
| In the first photo, the PM12 starter manufactured by EKF. The second photo shows the bridge-type auxiliary contacts:
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The first photo shows the crane contactor KT 6023. In the second photo, alternating auxiliary contacts (from top to bottom):
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The motherboard is the most important component of a computer, because it is where the rest of the hardware is connected. In some cases, it refuses to start when the power button is pressed. Today we will tell you how to act in such a situation.
The lack of response to the power supply indicates, first of all, a mechanical failure of either the button itself or one of the board elements. To exclude the latter, diagnose this component using the methods described in the article below.
Having ruled out the breakdown of the board, you should examine the power supply: the failure of this element can also make it impossible to turn on the computer from the button. The guide below will help you with this.
If the board and PSU are in good condition, the problem is most likely in the power button itself. As a rule, its design is quite simple, and, as a result, reliable. However, the button, like any other mechanical element, can also fail. The instructions below will help you troubleshoot the issue.
Method 1: Power button manipulation
A defective power button must be replaced. If this option is not available, it is possible to turn on the computer without it: you need to supply power by closing the contacts or connect the Reset button instead of Power. This method is quite complicated for a beginner, but it will help an experienced user to cope with the problem.
The disadvantages of such solutions to the problem are obvious. First, both the closure of contacts and the connection "Reset" create a lot of inconvenience. Secondly, actions require certain skills from the user that beginners do not have.
Method 2: Keyboard
The computer keyboard can be used not only to enter text or control the operating system, but can also take over the functions of turning on the motherboard.
Before proceeding with the procedure, make sure that your computer has a PS / 2 connector, such as in the image below.
Of course, your keyboard must be connected to this connector - this method will not work with USB keyboards.
As you can see, even such a seemingly difficult problem is very easy to fix. In addition, using this procedure, you can connect the power button to the motherboard. Finally, we remind you that if you think that you do not have enough knowledge or experience to carry out the manipulations described above, contact the service center!
Those who have computers for a long time often complain about some problems. One of them is a malfunction of the power button. Periodically, they fail for good, and then the question becomes relevant: how to turn on the computer without the power button?
general information
It also happens that there is power in the network, the motherboard signals its operation with its LED, but when you press the power button, nothing happens. The computer just won't turn on! What to do in this case? How to turn on the computer without the power button and preferably not in a very complicated way?
It should be noted that there can be an extremely large number of reasons for such behavior of technology. Within the framework of the article, several of the most popular options for failure and their elimination will be considered. Those that can be easily repeated at home will be given. If none of the below can help, then it would be better to turn to professionals so that they can fix the problem.
Quick but difficult check
Initially, you need to check the performance of the power supply:
- To do this, first disconnect all connectors (from the video card, motherboard, hard drives, cooler, etc.).
- You need to short two wires on the widest connector of those that are on the power supply. As a rule, it is green and the nearest black. You can do this with a regular paper clip or tweezers.
- We supply voltage from the outlet. And if the fans did not work, and everything was done correctly, then we can confidently say that the fault is in the power supply. If they start, then we can state that it is working.
Now you can connect the connectors back and solve the next problem.
How to start the computer?
So, we found out that the problem is in the computer itself. What to do now? The motherboard has many connectors to which the elements of the front panel of the computer case are connected - buttons, LEDs, USB ports and other components. The connectors for the power button are usually located on the bottom right side of the board. But it would be best to open the documentation for the element used and figure out where it has contacts. If it is not there, then you need to find the inscriptions: “Turn on / off” in English (Power Switch (PW Switch), Power ON, On-Off). After that, remove the connectors and carefully close the PWR SW and Ground contacts. How? Yes, even with a ballpoint pen.
Here's how to turn on your computer without the power button. And if after that everything works, then we know exactly what the problem is. It's in the on/off button itself. But what to do after finding out this fact? Of course, repair or replace it. For a while, you can also get out of the situation with the help of the reset button, connecting it, instead of the broken one. It is usually signed Reset.
In this simple way, you can make the technique work. And if the power button is broken, then we can recommend fixing it as soon as possible in order to avoid this problem. But be careful - with inexperience or connivance, the computer can be seriously damaged. Therefore, you should engage in a full repair only at your own peril and risk. Fortunately, you can use the reset button for a very long time.
Working with keyboard shortcuts
The keyboard is a part of the computer that is very much underestimated. Perhaps, answering the question of how to turn on the computer without the power button, one should have started with this method, which is both simple and easy.
To do this, we will have to work with the basic input / output system. True, everything is not so easy here. The fact is that for the successful use of this method, the keyboard must be connected not to a USB port, but to a round PS / 2. If this is not so, then, alas, nothing will work.
If the keyboard is what we need, then you need to set the setting (namely, select the items that correspond to the buttons that can turn on the computer using the keyboard). It could be either Space Bar (space), or Power Key (the power button found on "extended" keyboards) or Ctrl-Esc. After that, you should save the settings and turn off the computer to try out this innovation.
How to find the necessary property? Once you have logged into the basic I / O system, you should go to the Power Management Setup section and change On by Keyboard. And here we have an illustration to the question of whether it is possible to turn on the computer without the power button.
Features of technical design
As one person said, only a Soviet-made cast-iron frying pan can be more reliable than the power button. And well, it should be noted that there is a significant amount of truth in these words. Therefore, if the button is then here you can think about whether it is worth changing the piece of equipment? After all, this is one of the most basic elements of a PC, so when it fails, we can say that the operation literally rolls over. Or the equipment of clandestine production from China was bought. To prevent this from happening, you need to be careful when choosing a computer at the time of its purchase.
Safety
And now I want to go back a little and talk about safety. It should be noted that most computer elements operate at low voltage, which is units or even fractions of a volt. But not everything is so simple - because otherwise it would not be connected to a 220 V network. Therefore, always, even with the smallest cosmetic changes, it is necessary to completely de-energize the equipment from any voltage supply. Of course, this is quite laborious, but remember that all safety precautions are written in someone's blood.
Let's look at a small example of negligence. Here is a computer whose system unit is very difficult to completely disconnect from the power supply. It is put to sleep and the sidebar opens. And then an interrupt is triggered (for example, from a message that came over the network) and the equipment turns on. The current is unlikely to strike, but the fan on the motherboard can go hand in hand well. He, of course, will not cut off his fingers, but he will be able to noticeably beat them with his blades.
Conclusion
So we sorted it out, but these were the most primitive ways of checking the status and activation. It should be noted that there is a fairly large number of various auxiliary equipment with which you can restore and start literally dead electronics. But as a rule, experienced professionals who have been engaged in this business for quite a long time have it.
Although, as previously mentioned, with such a breakdown, it is still better to think about replacing the system unit. After all, in this case, you can remove all the “insides” from it and rearrange it into a new one. And this will save all the existing developments, and the replacement will be forgotten in a few days.
