What is maximum discharge current of a circuit breaker

The maximum discharge current of a circuit breaker, also known as the "short-circuit current" or "peak let-through current", is the maximum current that a circuit breaker is designed to interrupt or clear in the event of a short circuit or fault.

The maximum discharge current of a circuit breaker is typically specified by the manufacturer and is usually expressed in amperes (A). It is an important parameter that determines the circuit breaker's ability to safely interrupt a fault current and prevent damage to the equipment and personnel.

The maximum discharge current of a circuit breaker is influenced by several factors, including:

  1. The type and rating of the circuit breaker: Different types of circuit breakers, such as air-break, oil-break, or vacuum-break, have different maximum discharge currents.
  2. The voltage rating of the circuit breaker: Higher voltage-rated circuit breakers typically have higher maximum discharge currents.
  3. The fault current duration: The longer the fault current persists, the higher the maximum discharge current that the circuit breaker must be able to interrupt.
  4. The type of fault: The maximum discharge current required to interrupt a fault depends on the type of fault, such as a single-phase or three-phase fault.

Typical maximum discharge currents for different types of circuit breakers are:

It's important to note that the maximum discharge current of a circuit breaker should not be exceeded, as this can cause damage to the breaker or the equipment it is protecting.