Insulation Resistance and High-Potential Testing: Advantages and Limitations

Downtime caused by electrical equipment breakdown or cable faults can often be substantially reduced by the use of highvoltage dc testing as a maintenance tool. The relative merits of ac versus dc testing, general principles of dc testing, types of tests, methods of performing the actual tests, and interpreting the results are explained. The value of insulation resistance measurements and their relationship to testing is discussed. Safety precautions are also given.