Let's briefly introduce how to select a vacuum circuit breaker based on the capacity of the transformer:
1. 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, which is equipped with a spring operating mechanism. It can be AC, DC electric operation or manual operation; for indoor removable type For 10KV switch cabinet (such as KYN type), VS1 type vacuum switch can be selected, equipped with a spring integrated operating mechanism, which can be AC, DC electric operation, or manual operation;
2. Select the rated current of the circuit breaker. Generally, there are four types of 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 its rated current after leaving a margin; for a 2000KVA transformer, the other Rated current I=2000/(1.732*10)=115.5A. A 630A circuit breaker can be initially selected, but it should be calibrated;
3. Verify the breaking current of the selected circuit breaker. Calculate the short-circuit current value at the installation site of the circuit breaker and compare it with the initially selected breaking current value of the circuit breaker. After leaving a margin for the circuit breaker breaking current value, it should be greater than the maximum short-circuit current value at the installation site, so that It is guaranteed that the circuit breaker can operate reliably when a short circuit occurs, and the fault can be removed without being damaged. Generally, the rated short-circuit breaking current values of 10KV vacuum circuit breakers are mostly 20KA, 25KA, 31.5KA, and 40KA, corresponding to the 630A above respectively. , 1000A, 1250A, 1600A four rated currents; if the installation location of the 2000KVA transformer is relatively close to the substation exit and the maximum short-circuit current value is 26KA, then choosing a 630A switch with a rated short-circuit breaking current of 20KA cannot meet the use point meet the requirements; you should choose a circuit breaker with a rated current of 1250A and a rated short-circuit breaking current of 31.5KA.
4. Verification in other situations. Such as phase distance, installation size, interlocking situation, whether there is a lock, whether it has an overcurrent coil, whether it has a loss of voltage, etc.