Vacuum Circuit Breaker Troubleshooting

1 The vacuum degree of the vacuum bubble decreases

1.1 Fault phenomenon

The vacuum circuit breaker interrupts the current and extinguishes the arc in the vacuum bubble, but the vacuum circuit breaker itself does not have a device to qualitatively and quantitatively monitor the characteristics of the vacuum degree, so the vacuum degree reduction fault is a hidden fault, and its degree of danger is much greater than the explicit fault. .

1.2 Cause analysis

The main reasons for the reduction of vacuum degree are as follows:

(1) There are problems with the material or manufacturing process of the vacuum bubble, and there are tiny leaks in the vacuum bubble itself;

(2) There is a problem with the material or manufacturing process of the corrugated tube in the vacuum bubble, and leaks appear after multiple operations;

(3) Split vacuum circuit breaker, such as a vacuum circuit breaker using an electromagnetic operating mechanism, during operation, due to the relatively large distance of the operating linkage, directly affects the synchronization, bounce, overtravel and other characteristics of the switch, reducing the vacuum degree The speed increases.

1.3 Failure hazards

The reduction of vacuum degree will seriously affect the ability of the vacuum circuit breaker to interrupt overcurrent, and cause the service life of the circuit breaker to decrease sharply. In severe cases, it may cause the switch to explode.

1.4 Treatment method

(1) During regular power outage maintenance of the circuit breaker, a vacuum tester must be used to qualitatively test the vacuum degree of the vacuum bubble to ensure that the vacuum bubble has a certain degree of vacuum;

(2) When the vacuum degree decreases, the vacuum bubble must be replaced, and characteristics such as stroke, synchronization, and bounce must be tested.

1.5 Precautions

(1) When selecting a vacuum circuit breaker, you must choose mature products produced by reputable manufacturers;

(2) Choose a vacuum circuit breaker whose body and operating mechanism are integrated;

(3) During inspection, the operating personnel should pay attention to whether there is discharge phenomenon outside the vacuum bubble of the circuit breaker. If there is discharge phenomenon, the vacuum degree test result of the vacuum bubble is basically unqualified, and the power should be cut off and replaced in time;

(4) When maintenance personnel perform power outage maintenance work, they must conduct characteristics tests such as synchronization, bounce, stroke, and overtravel to ensure that the circuit breaker is in good working condition.

2 Vacuum circuit breaker opening failure

2.1 Fault phenomenon

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

(1) The circuit breaker cannot be opened remotely;

(2) The on-site manual opening cannot be opened;

(3) The relay protection operates during an accident, but the circuit breaker cannot be separated.

2.2 Cause analysis

(1) The opening operation circuit is disconnected;

(2) The opening coil is disconnected;

(3) The operating power supply voltage decreases;

(4) The resistance of the opening coil increases and the opening force decreases;

(5) The opening ejector rod is deformed, causing jamming during opening, and the opening force is reduced;

(6) The opening ejector rod is severely deformed and gets stuck during opening.

2.3 Failure hazards

If the opening failure occurs during an accident, it will cause the accident to escalate and expand the scope of the accident.

2.4 Treatment methods

(1) Check whether the opening circuit is disconnected;

(2) Check whether the opening coil is disconnected;

(3) Measure whether the resistance value of the opening coil is qualified;

(4) Check whether the opening ejector rod is deformed;

(5) Check whether the operating voltage is normal;

(6) Change the copper opening ejector rod to steel to avoid deformation.

2.5 Precautions

If the operating personnel find that the opening and closing indicator light is not on, they should promptly check whether the opening and closing circuit is disconnected; maintenance personnel should pay attention to measuring the resistance of the opening coil during power outage maintenance and check whether the opening ejector is deformed; if the opening ejector The material of the rod is copper and should be replaced with steel; a low-voltage opening and closing test must be carried out to ensure reliable performance of the circuit breaker.

3. Spring operating mechanism closing energy storage circuit failure

3.1 Fault phenomenon

(1) The opening operation cannot be realized after closing;

(2) The energy-storage motor does not stop running, and may even cause overheating and damage to the motor coil.

3.2 Cause analysis

(1) The installation position of the travel switch is lower, so that the closing spring has not yet completed the energy storage, the travel switch contacts have been converted, the motor power is cut off, and the energy stored in the spring is not enough for the opening operation;

(2) The installation position of the travel switch is upward, so that after the closing spring has stored energy, the contacts of the travel switch have not yet been converted, and the energy-storage motor is still in working condition;

(3) The limit switch is damaged and the energy storage motor cannot stop running.

3.3 Failure hazards

When the closing energy storage is not in place, if an accident occurs on the line and the circuit breaker refuses to open, it will cause the accident to escalate and expand the scope of the accident; if the energy storage motor is damaged, the vacuum switch will not be able to open and close.

3.4 Treatment methods

(1) Adjust the position of the travel switch to achieve accurate power-off of the motor;

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

3.5 Precautions

During the switching operation, the operating personnel should pay attention to the closing energy storage indicator light to judge the closing energy storage situation; after the maintenance work is completed, the maintenance personnel should perform two opening and closing operations on the spot to confirm that the circuit breaker is in Excellent condition.

4-point closing and closing phases are different and the bounce value is large.

4.1 Fault phenomenon

This fault is a hidden fault, and relevant data must be obtained through measurement with a characteristic tester.

4.2 Cause analysis

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

(2) Due to the large distance between the operating rods of the split circuit breaker, when the opening force is transmitted to the contacts, there is a deviation between the phases, resulting in different phases and larger bounce values.

4.3 Failure hazards

If the voltage is different or the bounce is large, it will seriously affect the ability of the vacuum circuit breaker to break overcurrent, affect the life of the circuit breaker, and in severe cases may cause the circuit breaker to explode. Since this fault is a hidden fault, it is more dangerous.

4.4 Treatment methods

(1) Under the premise of ensuring the stroke and over-travel, adjust the length of the three-phase insulating tie rod so that the synchronization and bounce test data are within the qualified range;

(2) If it cannot be achieved through adjustment, the vacuum bubble of the phase with unqualified data must be replaced and readjusted until the data is qualified.

4.5 Precautions

Since the split-type vacuum circuit breaker has many hidden faults, an integrated vacuum circuit breaker should be used when replacing the circuit breaker; during regular maintenance work, a characteristic tester must be used to conduct relevant characteristic tests so that problems can be discovered and solved in a timely manner.

HZC-3980 Circuit Breaker Analyzer