How does the AC variable frequency power supply perform the circuit breaker test?
With the development of society, people have higher and higher requirements for the safety and reliability of power consumption. The high-voltage circuit breaker is responsible for the dual tasks of control and protection in the power grid. Its performance is directly related to the safe operation of the electrical system. The reliability test is based on a good power supply configuration. The AC variable frequency power supply uses its settable and adjustable functions to provide a good test for test engineers. experience.
For primary power testing of low-voltage circuit breakers, inject high-intensity current into each phase of the low-voltage circuit breaker (usually 5 to 10V). The variable frequency AC constant current power supply is set to 10V500A or 1000A. The intensity of the injected current can be determined according to each manufacturer's recommended value or according to the value of the time current according to the curve specified by the manufacturer. The test circuit associated with each phase is normally powered by the breaker contacts and returned through the load contacts. Correct action of circuit breaker components (converter, conductors, contacts, trip mechanism and mechanical trip unit) is accomplished by performing a power injection test on each phase of the circuit breaker, according to the time-current curve of the circuit breaker, each The test currents all have the time response necessary to assess eligibility.
A power injection test has become the preferred test method for circuit breakers because it verifies sensors, wiring, triggers and conduction paths during shutdown. A power injection test is usually performed by an experienced test technician using a special power injection tester with built-in meters and transformers (which makes the tester very bulky and difficult to move). A power injection test can also be destructive because a large current must be supplied to the circuit breaker, mainly because the high current stress to which the circuit breaker is subjected may cause premature failure of the circuit breaker. Unfortunately, a one-shot injection test may be the only way to test certain low-voltage circuit breakers (eg, molded case circuit breakers, thermal circuit breakers, and thermal-magnetic circuit breakers).
The difference between the secondary power injection test and the primary power injection test is that no high current is applied through the power switch circuit to contact the load. The secondary power injection test usually does not connect the trip unit to the common monitoring circuit, but to special test equipment that can inject electricity, measure and record the action of the circuit breaker. The advantage of the secondary power injection test is that it can be The circuit breaker is tripped with current to allow the trip unit to operate during the test. The obvious disadvantage of the secondary power injection test is that it cannot test current transformers and certain contacts.
