Circuit Breaker tester

[ELECT 1]

What puzzles me, we have to do so many tests on an installation, and one of the most important tests that should be taken into account is a circuit breaker that trips at its rating.
Otherwise whats the point.
Some breakers seem to buzz, some just trip, some just get hot.....i feel strongly about this as this is a protection device.

[AndyD]

Testing circuit breakers is a straight forward operation but you need a primary current injection unit which will set you back about 350 thousand Rands plus shipping and import duties so it's only worth the investment if yu're setting it up as a primary business.

I suppose you could check up to 20A with a bench rig and check their disconnect times at 2 or 3 x their rating In value).

Circuit breakers tend to buzz when the load is highly inductive (AC3) or poor power factor/high harmonics. They run warm when they're loaded close to their rated value because of the internal thermal element assuming it's not poor terminations, all this would be normal behaviour.

The biggest causes of circuit breaker failure we come across (excluding the cheap rubbish that's obviously poorly manufactured) are poor terminations, debris inside the breaker (usually where some low-life has drilled above the panel or DB and not covered it) and excessive wear and tear usually when the customer is using the breaker frequently as an isolator. The damage from the first two would usually be obvious without complicated testing.