Reasons for repeated switching in the operation of the electronic control system

As a movement to complete the corresponding electrical equipment of electric control system, believe the electrician is not a stranger. So I wonder if everyone at work met the situation - the originally carried out in accordance with the motion commands below switch or transformation of electrical devices and has repeatedly switch back and forth or action before they can complete the task, even can't finish the task? Due to work I dispose of this kind of situation, many times, so today I will be the cause of this abnormal situation occurs, do sum up with everyone together to explore the road.

The situation mentioned above, I think in the final analysis the reason has three aspects:

When the electric circuit design staff not effectively in combination with the practical action process of control system, or process equipment operation action, only in the theoretical level, often can cause the abnormal situation. Such as electromagnetic contactor complete absorption merger self-locking process take about 500 ms, but the designer sets the action command signal to rise along/down along the pulse signal, the output effective length is about 1 to 2 ms), so the contactor in action is necessarily । repeatedly

Traditional electromagnetic relay, contactor, such as electronics, on and off or release produced during the vibration is inevitable, and the bigger the contactor main contact capacity, it also produces vibration is larger. But as auxiliary control terminals are usually very small, so in a long period of time after exposure to the vibration impact, such as fastening bolt looseness, slip the possibility of virtual connect situation greatly. So must jointly and severally, related electrical equipment movement disorders or failure!

Besides electrical own vibration factor, electronic control system used to wiring of the base of time relay contactor, small plug type/relay, etc., due to the oxidation of be affected with damp be affected with damp or elastic reeds in base, indirectly causing virtual, conduction resistance increases, the phenomenon such as loose device, thus affect the normal control circuit corresponding movement, rapid transformation is carried out. Of course the happening of this kind of circumstance also is to have rules to follow - hot humid summer weather; Install and use time more than a year, particular attention must be paid.

At present a lot of impact on power grid entities electromagnetic interference of industrial control equipment, is widely used. This part of the equipment including inverter, inverter welding machine, high frequency heating equipment in familiar devices, they are all typical electromagnetic interference sources. If in the electric control system, according to these measures to prevent electromagnetic interference sources such as shielding, grounding processing does not reach the designated position, are highly vulnerable to the interference of other electrical equipment, cannot normal operation happened even failure phenomenon is very strange

Last October, the author once went to a unit overhaul electric control cabinet. The unit one in electrical control cabinet of dc 24 v relay operation system, in the so-called often occurs after transforming slow action, and bad, and so on and so forth, back and forth, and used to provide power AC220V/DC24V relay switch power supply is also often burned fault! When open the control cabinet, I glance at finding out the cause that the crux of the problem - the unit in order to save money, in the control cabinet shoehorned into the two 5.5 KW inverter, more important is for the two inverter do not make any electromagnetic interference filter action!

To sum up, when the electronic control system electrical equipment operation happened repeatedly switch back and forth, the abnormal situation such as action, you can reference cited three possibilities of induced failure phenomenon, a serious overhaul, and take corresponding measures to improvement.