Vacuum circuit breakers are currently widely used in industrial production and distribution, with common products such as VS1-12 vacuum circuit breakers. However, due to their high rated voltage, high current, and strong flying ability, there are many problems and hidden dangers. Improper handling can lead to many accidents. Therefore, this requires us to strengthen management in the selection, installation, operation, and maintenance of vacuum circuit breakers, monitor and diagnose the status of the operating vacuum circuit breakers, and promptly and accurately handle common faults.
vacuum circuit breaker
1. Debugging and handover tests must strictly control the debugging and handover tests of the equipment to prevent any changes during transportation or mismatches that may occur after adjusting the mechanism, especially after connecting the operating mechanism to the vacuum circuit breaker. The main parameters to be retested include: closing bounce, opening synchronization, opening distance, compression stroke, closing and opening speed and time, DC resistance, opening and closing action voltage value, fracture insulation level, transmission acceptance test, etc. All of these parameters should meet the requirements. In our routine maintenance work, we mainly found the following problems: the expansion baffle of the static contact in the circuit breaker cabinet and the handcart circuit breaker frame got stuck, causing difficulty in entering the vehicle, the bounce and stroke of the circuit breaker were not qualified, the insulator porcelain bottle of the circuit breaker body was damaged due to being too close to the pull rod, the closing contactor had poor operating characteristics, often unable to operate or the operating voltage gradually increased after one operation, and the vacuum degree of the vacuum bubble did not meet the requirements. We have dealt with these problems. The debugging and handover testing of vacuum circuit breakers must be strictly carried out. We need to promptly detect insulation breakdown, structural abnormalities, vacuum arc extinguishing chamber leaks, and abnormal bouncing, speed, and travel before putting it into operation to ensure safe operation.
2. Operation and maintenance, regular inspection
2. 1. During operation and maintenance, pay attention to observing for any abnormal phenomena, such as abnormal discharge sounds after the circuit breaker is disconnected. When powering on, observe for cracks or damage in the vacuum arc extinguishing chamber. Report any abnormalities immediately and wait for maintenance confirmation before proceeding with the operation.
2.2. Regular inspection of common defects in the vacuum circuit breaker body includes: leakage of the vacuum arc extinguishing chamber, breakdown of the insulation parts of the body, unqualified overvoltage protector, unqualified DC resistance of the vacuum arc extinguishing chamber, and refusal to close the circuit breaker when put into operation. Regular withstand voltage tests, measurement of vacuum degree, determination of DC resistance and opening and closing action voltage values are important means of discovering the above-mentioned defects.
3. Status Monitoring and Diagnosis of Vacuum Circuit Breaker
The vacuum arc extinguishing chamber is a key component of a vacuum circuit breaker. It is supported and sealed with glass or ceramic, and contains dynamic and static contacts and shielding covers. The vacuum degree should not be lower than 6.6 x 10-2P a. The vacuum arc extinguishing chamber manufactured by the factory is required to be below 7.5 x 10-4Pa. When the vacuum degree decreases, its breaking performance significantly decreases. Therefore, the vacuum arc extinguishing chamber cannot be struck or impacted by any external force.
3.1 Inspection of Vacuum Arc Extinguishing Chamber The characteristic of a vacuum circuit breaker is that the contacts are sealed inside the insulated shell of the vacuum arc extinguishing tube. It is manufactured using modern equipment under strict quality management, ensuring a long service life. Inspection is required in the following situations, if necessary
Need to replace vacuum bubble:
(I) When the vacuum arc extinguishing chamber has reached the guaranteed number of on-off cycles by the manufacturer (mechanical life of 10000 cycles);
(2) The vacuum arc extinguishing chamber has reached the specified inspection cycle (when the number of opening and closing cycles reaches 10000 times and the short-circuit current reaches 100 times, the withstand voltage test of the arc extinguishing chamber is carried out, and when it reaches 20000 times, the vacuum arc extinguishing chamber is replaced);
(3) When abnormalities are found in appearance. Inspection basis: The lifespan of a vacuum circuit breaker is determined by two indicators: the contact and vacuum degree
(1) Measure contact wear. Mark the contact rod of the vacuum circuit breaker to check or measure the contact overtravel with a vernier caliper. If the accumulated wear thickness of the moving and stationary contacts exceeds the specified range, it indicates that the electrical life of the vacuum bubble has ended and the vacuum bubble should be replaced.
(2) The DC resistance of the vacuum bubble is within the specified range. The DC resistance of a general vacuum bubble is not greater than 25 μ Ω, and the conductive circuit resistance of a vacuum circuit breaker is not greater than 45 μ Ω
(3) Vacuum degree measurement.
① Power frequency withstand voltage method. Place the circuit breaker in the open state and apply voltage between the contacts of the vacuum arc extinguishing chamber to determine if it can withstand 42kV and Imin power frequency withstand voltage tests. If there is no continuous discharge inside the vacuum bubble, it is considered normal.
② ****** Testing. The currently better method is the magnetron method, which is suitable for testing vacuum arc extinguishing chambers in manufacturing plants. The vacuum degree is not greater than 5 * 10-4Pa,
③ Spark gauge method. Only applicable to glass tube vacuum arc extinguishing chambers. When in use, move the spark leak detector on the surface of the arc extinguishing chamber, and there will be different luminescence situations inside under the action of its high-frequency electric field. If there is a light blue glow inside the tube, the vacuum degree should be above 1.33 * 10-5; If it shows red and blue light, it indicates that the tube has failed; If the tube is already in an atmospheric state, it will not emit light.