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Expression of technical parameters of moulded case circuit breaker

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ICU: rated limit short-circuit breaking capacity refers to the breaking capacity that the circuit breaker can not continue to carry its rated current capacity according to the conditions specified in the test procedure o-t-co. That is, the circuit breaker can reliably break the short-circuit current. The circuit breaker can continue to be used only under certain constraints.

ICS: rated operating short-circuit breaking capacity refers to the breaking capacity of the circuit breaker which can continue to carry its rated current capacity according to the conditions specified in the test procedure o-t-co-t-co. That is, the maximum short-circuit current that the circuit breaker can reliably break. After the short-circuit current is cut off, the circuit breaker can still be used.

ICM: rated short-circuit making capacity refers to the short-circuit current that the circuit breaker equipment can make under the condition of rated working voltage - 10%, rated frequency and specified power factor according to the conditions specified in the test procedure o-t-co-t-co.

The expression method of technical parameters of MCCB. In general, ICU ≥ ICs, ICM = nxics; the ICU of Schneider MCCB is generally 15, 25, 36 KA

Note: O - off; t - intermittent time; co - on and off.

In =160 A

Io=In x .9=144A

Ir=Io x .95=136.8A

Im=Ir x 6=820.8A

Isd=Irx2=273.6A

Where in is the rated current of the release, if the setting value is not set, the current through the circuit breaker will trip when it reaches 160A; IO is the setting current of the release, if you want the circuit breaker to trip when it is less than 160A, such as 144A (coefficient of 0.9), once the current through the circuit breaker reaches 144A, the release will trip, and the circuit breaker will trip; or you think this is not safe enough Because 144A is already your bottom line. If you want to cut off the power supply when the current reaches 144A, you can set the overload long delay setting current of the release, i.e. IR = 0.95 * 144 = 136.8a; IM is the short-circuit setting current of the release, which is usually a multiple of the overload long delay setting current IR, such as 6 times IR * 6 = 820.8a, Also known as short-circuit instantaneous, the action time of the tripping mechanism is generally ms level; ISD short-circuit short delay, its setting value can also be set according to the actual situation, but the action time of the tripping mechanism is generally 0.1s ~ 1s, which is faster than the action time of the superior circuit breaker.

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