The standard behind the contact resistance test on high-voltage switchgear and circuit breakers is IEC 62271-1. It doesn’t use the phrase “contact resistance” — it calls the test “measurement of the resistance of the main circuit.” The method is a DC measurement across the contacts, taken as the average of three readings, at a test current of at… Read More: Contact Resistance Test: The IEC 62271-1 Standard »
The standards don’t change when you move from medium to high voltage. IEC 62271-1 and IEC 62271-100 cover every AC circuit breaker above 1 kV, so the same three-tier logic applies — type tests for the design, routine tests for the unit, field tests for the condition. What changes is the severity of the duties and the complexity… Read More: HV Circuit Breaker Testing: What Changes Above 52 kV (IEC… »
A medium-voltage circuit breaker has one job that matters above all others: interrupt a fault current safely, on demand, possibly after sitting closed and untouched for years. Testing exists to prove it still can. But “circuit breaker testing” covers three completely different activities done by three different people in three different places — and most of the confusion… Read More: MV Circuit Breaker Testing: Type, Routine & Field Tests (IEC… »