When a fault such as a short circuit or current overload is detected by a protective relay, a trip impulse is sent to the circuit breaker. The circuit breaker must function as specified and interrupt the current as soon as possible or severe damage may occur. The damage caused by a malfunctioning circuit breaker can often be catastrophic, resulting in significant damage to the electrical system.
Having good insulation on electrical equipment is rather like having a water tank in your loft that’s actually watertight. In both cases, the cost of repairing an actual fault – whether it’s poor insulation or a leaking tank – is likely to be much less than the cost of repairing the damage caused by the fault. Nevertheless, how many people actually take the trouble to look occasionally at their water tanks to check that they are in good order? Not many, I suspect, even though doing so could potentially save a lot of money and heartache.
A summary of insulation testing method and a guide to selecting the right instruments for the job.
A look at the technology behind the TDR and its many uses.
A TDR (time domain reflectometer) uses the radar principle to identify faults on cables. This paper shows how to operate it correctly.