Question: What is breaking capacity of circuit breakers and how it is expressed?
Answer: The breaking capacity of circuit breakers is rated RMS current that a circuit breaker is capable of breaking at rated recovery voltage.
Explanation
The breaking capacity of CB is rated current at which a CB is capable of breaking the circuit at the given recovery voltage.
Breaking capacity is rated in terms of MVA. Where:
A represents rated RMS short circuit current
V represents recovery voltages
The reason for using recovery voltage instead of fault voltages is the fact that voltage is very small during the short circuit condition.
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