Breaking capacity of a circuit breaker is usually expressed in MVa.


Circuit breakers are electrical devices that protect electrical circuits from damage caused by overload, short circuit, or any other fault condition. They are designed to interrupt the flow of current when there is a fault in the system. The breaking capacity of a circuit breaker refers to its ability to interrupt or break the flow of current under fault conditions.


The breaking capacity of a circuit breaker is usually expressed in Mega Volt-Amperes (MVA). This unit is used because it represents the product of the voltage and current that the circuit breaker can interrupt.

The breaking capacity of a circuit breaker is determined by two factors:

1. Voltage:
The voltage rating of a circuit breaker determines the maximum voltage at which it can operate safely. It is important to select a circuit breaker with a voltage rating that matches or exceeds the voltage of the electrical system it is installed in. However, the breaking capacity of a circuit breaker is not directly related to its voltage rating.

2. Current:
The current rating of a circuit breaker determines the maximum current that it can safely interrupt. This is usually expressed in Amperes (A). The breaking capacity of a circuit breaker is directly related to its current rating. A circuit breaker with a higher current rating will have a higher breaking capacity.


The breaking capacity of a circuit breaker is a crucial specification as it determines the level of fault current that the breaker can safely interrupt. If the fault current exceeds the breaking capacity of the circuit breaker, it may fail to interrupt the current, leading to damage or even catastrophic failure of the electrical system.

By expressing breaking capacity in MVA, it allows for a standardized unit that takes into account both voltage and current. This helps in selecting the appropriate circuit breaker for a given electrical system, ensuring that it can safely interrupt the fault current and protect the system from damage.

In conclusion, the breaking capacity of a circuit breaker is usually expressed in Mega Volt-Amperes (MVA) to indicate its ability to interrupt the flow of current under fault conditions.