A brief introduction to how to choose a vacuum circuit breaker by the capacity of the transformer

Select the type of vacuum circuit breaker according to the cabinet type. For indoor fixed 10KV switch cabinets, most of them use ZN28 vacuum switch, equipped with a spring operating mechanism, which can be operated by AC and DC electric operation or manual operation; for indoor removable type 10KV switch Cabinet (such as KYN type), VS1 type vacuum switch can be selected, equipped with a spring integrated operating mechanism, which can be operated by AC and DC electric operation, and can also be manually operated;

The rated current of the selected circuit breaker. Generally, there are four types of power distribution circuit breakers: 630A, 1000A, 1250A, and 1600A. You should calculate the load current flowing through the circuit breaker according to the load situation, and then select the rated current after leaving a margin; for a 2000KVA transformer, its Rated current I=2000/(1.732*10)=115.5A, a 630A circuit breaker can be selected initially, but it should also be verified;

Verifies the breaking current of the selected circuit breaker. Calculate the short-circuit current value of the installation site of the circuit breaker, and compare it with the breaking current value of the circuit breaker that was initially selected. After leaving a margin, the breaking current value of the circuit breaker should be greater than the maximum short-circuit current value of the installation site, so as to ensure In the event of a short circuit, the circuit breaker can operate reliably and remove the fault without being damaged. Generally, the rated short-circuit breaking current value of 10KV vacuum circuit breaker is mostly 20KA, 25KA, 31.5KA, 40KA, corresponding to the above 630A, Four rated currents of 1000A, 1250A and 1600A;

If the installation site of the 2000KVA transformer is relatively close to the outlet of the substation, and the maximum short-circuit current is 26KA, then the rated short-circuit breaking current of the 630A switch is 20KA, which cannot meet the requirements of the point of use; The short-circuit breaking current is a circuit breaker of 31.5KA.

Check in other cases. Such as phase-to-phase distance, installation size, interlocking situation, whether there is blocking, whether it has an overcurrent coil, whether it has a voltage loss, etc.