Failure analysis of high voltage vacuum circuit breaker

Promulgator : TAIXIDate : 2018-07-16Views : 1799

High voltage vacuum circuit breaker (HV circuit breaker) is one of the key electrical appliances related to the effective control of power system. It can guarantee the normal and efficient operation of the circuit system only by maintaining its good running state. According to the key functions of the circuit breaker, it is necessary to detect the operating state of the vacuum circuit breaker in real time, and take corresponding measures to solve the problems in time. This article will share with you how to deal with the breakdown of HV vacuum circuit breakers, hoping to provide a reference for the majority of users.

One. The failure of a general high voltage vacuum circuit breaker

Fault of circuit breaker, failure of energy storage mechanism, reduction of vacuum degree, damage of arc extinguishing ability, decrease of arc extinguishing chamber of arc extinguishing chamber, etc.

Two. The cause analysis of failure

1. Anti-opening and anti-closing of circuit breaker

The main cause of the circuit breaker's failure to operate is two aspects of circuit breaker's circuit fault and mechanical part fault. It is necessary to solve the problem according to the different reasons. When there is no fault in the detection of the two circuit, we should observe the length of the clearance of the universal shaft connected by the main arm of the operating mechanism. In some cases, when the gap is too large, it can make the operating machine run normally, but in this case, the connecting rod of the circuit breaker can not be driven, and eventually it is caused. The circuit breaker can not be divided regularly, so the gap should be kept within a certain range.

2. Misdivision of high voltage vacuum circuit breaker

When the circuit breaker is under normal operation, do not rush to break the circuit breaker when there is no external power supply and mechanical separation. To ensure that all operations are accurate, the two loop and action mechanism should be carefully tested. If there is a short circuit in the operating mechanism, the power will break through the break coil and the short circuit point, which will cause the vacuum circuit breaker to be mistakenly divided and closed. The main main factor that causes the wiring short circuit is the leakage at the top of the circuit breaker, and the rain and the output arm are connected to a line that happens to be in contact with the auxiliary switch of the mechanism.

3. After storage of the circuit breaker, the energy storage motor is stopped

The energy storage motor can operate only after the circuit breaker is closed, and the spring energy storage indicator will be issued after the spring energy accumulates. When the spring energy is satisfied, the stroke switch is closed, the energy storage circuit is connected, the motor is electrified and keeps running.

4. The increase of DC resistance of the circuit breaker

Because the contact of the vacuum interrupter is the butt type, the contact resistance of the contact is more than the actual loading range, which will lead to the rise of the contact temperature when the current is carried, which usually leads to the appearance of the electrical and breaking circuits, so the contact resistance must not be greater than the maximum value specified in the manual. The contact spring pressure directly affects the size of contact resistance. Therefore, it is necessary to carefully check whether the super stroke meets the requirements before measuring. If the contact resistance value continues to rise, it will also reflect the degree of electric contact loss to a certain extent, and the relationship between them is mutual influence. The key factor that leads to the increase of DC resistance of circuit breaker is the electrical wear of contacts and the change of contact distance of circuit breakers.

5. The jumping time of the switch on the circuit breaker is increased

Generally, the vacuum circuit breaker often occurs when the contact is closed, but if the range of the jumper exceeds the specified limit, it will cause a burn or welding of the contact. The decline of spring performance and wear of the crank arm and shaft often lead to the increase of the closing time of the vacuum circuit breaker.

6, the CT surface of the middle box of the circuit breaker to the support discharge

The discharge of the circuit breaker to the bracket is due to the uneven electric field generated on the surface of the current transformer (CT). The intermediate box of the vacuum circuit breaker is equipped with a current transformer. When the current transformer does not take measures, an unbalanced electric field will appear on the CT surface when the circuit breaker operates. Therefore, to prevent such a situation as far as possible, a layer of semiconductor glue is applied to the surface of the transformer before the transformer is out of the factory, so that the balance of the electric field can be guaranteed. If the semiconductor gum is affected when the circuit breaker is assembled, it will still cause an uneven electric field on the surface of the transformer during the operation of the circuit breaker, resulting in the discharge of the stent on the surface of the transformer.

7. The interrupter of the circuit breaker can not be disconnected

Under normal circumstances, circuit breakers are cut off, and the main reason for current cut-off is manual operation and protection trip. The arc extinguishing principle of vacuum circuit breaker is different from other types of circuit breakers because the circuit breaker usually uses vacuum as insulation and arc extinguishing medium.

If the vacuum degree of the vacuum bubble is not satisfied, it often causes ionization in the vacuum bubble, which will inevitably lead to the emergence of the electric ion, which will undoubtedly weaken the insulation of the arc extinguishing chamber, because these factors will always be in the connection state.