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Why is it important to test circuit breakers?

time:2021/4/18   source:华天电力  reading:495 time

Why is it important to test circuit breakers?

 

The circuit breaker may remain idle for several years, but if it fails, the large kiloampere fault current must be gradually separated within a few milliseconds. The main errors that occur on circuit breakers are incorrect behavior, short-circuited coils, damaged/worn mechanical connections or insulating materials. Therefore, the circuit breaker needs to be carefully tested on a regular basis. Circuit breakers play a vital role in protecting expensive equipment from failures, namely connecting and disconnecting power in a reliable manner; this requires field testing during installation and regular maintenance tests during its life to prove it. Reliability to prevent costly failures and issues that may even endanger the safety of the substation. Therefore, regularly testing the performance of the circuit breaker is an essential and cost-effective part of any maintenance strategy. Circuit breaker testing is particularly focused on obtaining movement and time values on the unit. However, our testing solution completely changed circuit breaker testing. Performing the test without using the station battery can greatly improve the safety of the entire test process.

 

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What are the steps for circuit breaker testing?

 

The purpose of organizing type testing is to prove the capability and ensure that the rated characteristics of the circuit breaker are accurate. Such tests are carried out in specially established test laboratories.

 

1. Mechanical test-a mechanical capability test involving repeated opening and closing of the circuit breaker. The circuit breaker must close and open at an appropriate speed, and complete its assigned work and functions without any failure.

 

2. Thermal test-Conduct a thermal test to check the thermal performance of the circuit breaker. Since the rated current flows through the poles under rated conditions, the circuit breaker under test will experience a steady-state temperature rise. For the current less than 800A normal current, the temperature rise of the rated current should not exceed 40°, and for the normal value of 800A and above, it should not exceed 50°.

 

3. Dielectric test-perform these tests to check the power frequency and pulse voltage withstand capability. The power frequency test is saved on the new circuit breaker; the test voltage varies with the rated voltage of the circuit breaker. In the impulse test, a specific value of impulse voltage is applied to the circuit breaker. For outdoor circuits, dry and wet tests are performed.

 

4. Short circuit test-The circuit breaker has a sudden short circuit in the short circuit test laboratory, and when it is turned on, during the contact disconnection and after the arc is extinguished, use the waveform diagram to understand the behavior of the circuit breaker. Special reference is made to manufacturing and breaking currents, symmetrical and asymmetrical restriking voltages to study waveform diagrams, and sometimes to test switchgear under rated conditions.

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