What is the reason why the overload protection trips as soon as the laboratory muffle furnace starts heating?
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A multimeter test showed no short circuit between the heating wire and the casing, but the circuit breaker trips as soon as power is applied and the temperature starts to rise
I think there are two reasons: one is tripping due to overload, and the other is tripping due to electric leakage. We can check whether the reset button on the circuit breaker has popped up; if it has, then the tripping is caused by electric leakage. If it hasn’t popped up, it means the tripping is due to overload. Of course, it’s necessary to ensure that the circuit breaker being used is accurate and functional.
A muffle furnace is a heating device, and its temperature should not be high when measured with a multimeter. However, when a muffle furnace is in use, the high temperature causes a decrease in the insulation of the electrical components, resulting in electric leakage. If it is confirmed to be a leakage trip.
Could you explain the principle behind how high temperatures lead to a decrease in insulation performance? Thank you
At a visual inspection, the insulation of the heating wire is no longer effective; the high temperature has caused a ground fault and a shutdown
First, use an insulation megger to check the insulation level; many multimeters cannot detect leaks in insulation
Thank you. It’s indeed impossible to measure it with a multimeter