Vacuum circuit breaker common faults and treatment methods

With the wide application of vacuum circuit breakers in the power industry, some vacuum circuit breakers have better performance, small maintenance and maintenance workload, and high power supply reliability. Some vacuum circuit breakers have poor performance and some problems are compared. There are also some vacuum circuit breakers that are extremely serious and are prone to cause accidents, resulting in large-scale power outages. Next, we walked into the field where the electrical engineer handled the vacuum circuit breaker failure, so that I also accumulated experience and comprehensive maintenance.

First, the vacuum bubble is reduced

Fault phenomenon

The vacuum circuit breaker breaks the current in the vacuum bubble and extinguishes the arc. The vacuum circuit breaker itself has no means for qualitatively and quantitatively monitoring the vacuum degree. Therefore, the vacuum degree reduction fault is a hidden fault, and the danger degree is far greater than the dominant fault. .

Cause Analysis

There is a problem with the material or manufacturing process of the vacuum bubble, and there are tiny leak points in the vacuum bubble itself;

There is a problem in the material or manufacturing process of the corrugated tube inside the vacuum bubble, and a leak occurs after multiple operations;

Split type vacuum circuit breaker, such as vacuum circuit breaker using electromagnetic operating mechanism, in operation, because the distance of the operating link is relatively large, directly affecting the characteristics of the switch synchronization, bounce, overtravel, etc., so that the speed of vacuum reduction is accelerated .

Fault hazard

The reduction in air vacancy will seriously affect the ability of the vacuum circuit breaker to open and over-current, and cause the life of the circuit breaker to drop sharply. In severe cases, the switch will explode.

Approach

When performing periodic power failure maintenance of the circuit breaker, the vacuum tester must be used to test the vacuum degree of the vacuum bubble to ensure that the vacuum bubble has a certain degree of vacuum;

When the vacuum is reduced, the vacuum bubble must be replaced, and the characteristics of the stroke, the synchronization, and the bounce are tested.

Precaution

When vacuum circuit breakers are used, mature products produced by reputable manufacturers must be selected;
Select a vacuum circuit breaker with a body and an operating mechanism;

When the operation personnel patrol, attention should be paid to whether there is a discharge phenomenon outside the vacuum bubble of the circuit breaker. If there is a discharge phenomenon, the vacuum degree test result of the vacuum bubble is basically unqualified, and the power should be replaced in time;

When the maintenance personnel perform power failure maintenance work, they must perform characteristic tests such as synchronization, bounce, stroke, and overtravel to ensure that the circuit breaker is in good working condition.

Second, the vacuum circuit breaker broke down

Fault phenomenon

Depending on the cause of the fault, the following faults exist:

The remote remote control of the circuit breaker can not be separated;

Manual manual opening can not be divided;

The relay protection action occurred during the accident, but the circuit breaker could not be separated.

Cause Analysis

The tripping operation circuit is broken;

The opening coil is broken;

Operating power supply voltage is reduced;

The opening coil resistance increases, and the opening force decreases;

Deformation of the ejector pin, there is a jam phenomenon when opening, and the breaking force is reduced;

The ejector lever is severely deformed and is stuck when it is opened.

Fault hazard

If the failure of the trip occurs in an accident, it will lead to an escalation of the accident and expand the scope of the accident.

Approach

Check if the opening circuit is broken;

Check if the opening coil is broken;

Measure whether the resistance value of the opening coil is qualified;

Check if the opening ejector is deformed;

Check if the operating voltage is normal;

Change the copper ejector pin to steel to avoid deformation.

Precaution

If the on-site duty electrician finds that the opening and closing indicator light is not bright, it should promptly check whether the opening and closing circuit is disconnected; the maintenance personnel should pay attention to measuring the resistance of the opening coil when checking the power failure, and check whether the opening ram is deformed; The material of the ram is copper and should be replaced with steel; low voltage switching test must be carried out to ensure reliable circuit breaker performance.

Third, the spring operating mechanism closes the energy storage circuit failure

Fault phenomenon

The opening operation cannot be realized after closing;

The operation of the energy storage motor does not stop, and even the motor coil is overheated and damaged.

Cause Analysis

The installation position of the stroke switch is lower, so that the closing spring has not been stored yet, the stroke switch contact has been converted, the motor power is cut off, and the stored energy of the spring is not enough to open the gate;

The installation position of the travel switch is on the upper side, so that after the energy storage of the closing spring is completed, the contact switch contact has not been converted, and the energy storage motor is still in working state;

If the travel switch is damaged, the energy storage motor cannot be stopped.

Fault hazard

In the case that the closing storage energy is not in place, if an accident occurs on the line and the circuit breaker refuses to open, the accident will be overstepped and the scope of the accident will be expanded. If the energy storage motor is damaged, the vacuum switch cannot be opened and closed.

Approach

Adjust the position of the travel switch to achieve accurate motor power off;

If the travel switch is damaged, it should be replaced in time.

Precaution

During the operation of the switch, the operating personnel should pay attention to observe the energy storage indicator of the closing to judge the energy storage of the closing; after the maintenance work is completed, the maintenance personnel should perform 2 closing operations on the spot to confirm that the circuit breaker is in operation. Good condition.

Fourth, different periods of closing and closing, large bounce value

Fault phenomenon

This fault is a hidden fault and must be measured by the characteristic tester to obtain the relevant data.

Cause Analysis

The mechanical performance of the circuit breaker body is poor. After multiple operations, due to mechanical reasons, the value of the bounce is too large;

The split type circuit breaker has a large distance between the operating rods, and when the opening force is transmitted to the contacts, there is a deviation between the phases, resulting in a large value in different periods and bounce.

Fault hazard

If the period is different or the bounce is large, it will seriously affect the ability of the vacuum circuit breaker to open and over-current, affecting the life of the circuit breaker, and causing the circuit breaker to explode in severe cases. Since this fault is a hidden fault, it is more dangerous.

Approach

Under the premise of ensuring the stroke and overtravel, the synchronization and bounce test data are within the qualified range by adjusting the length of the three-phase insulated tie rod;

If it cannot be achieved by adjustment, the vacuum bubble of the data failure phase must be replaced and re-adjusted until the data is qualified.

Precaution

Due to the many hidden troubles of the split vacuum circuit breaker, an integrated vacuum circuit breaker should be used when replacing the circuit breaker; the characteristic tester must be used for the characteristic test during the regular maintenance work, and the problem can be solved in time.

In addition, the harm of the environment to the equipment can not be ignored, provide a good working environment for the equipment, and ensure the safe and reliable operation of the vacuum circuit breaker.