Dielectric Test
A Dielectric Test, also known as a Hipot or Dielectric Withstand Test, is an electrical safety test that applies high voltage to a component to verify insulation system effectiveness by ensuring leakage current remains below a specified limit without breakdown or arcing. It qualifies a device's ability to operate safely under rated conditions and withstand momentary over-potentials from switching surges.
In manufacturing and shop-floor maintenance, technicians apply AC or DC high voltage between live conductors and grounded parts, ramping to the test level, holding for a defined duration, and monitoring leakage current. If leakage is below the threshold and no arc occurs, the asset passes; if current exceeds limits or arcing occurs, it fails, indicating damaged insulation or foreign material like water bridging the insulation. In CMMS like ServiceGrid, this is logged as a routine preventive maintenance task for motors, transformers, cables, and compressors, often triggered after mechanical abuse or temperature cycling.
How does a Dielectric Withstand Test differ from a Dielectric Breakdown Test?
Withstand tests apply a predetermined voltage to verify insulation integrity without destroying the asset; breakdown tests ramp voltage until the material fails to determine the dielectric breakdown voltage limit.
What is the standard pass criterion for a Dielectric Test?
Leakage current must remain below a pre-set allowable threshold with no arc or discharge detected during the hold time.
Which CMMS metric tracks Dielectric Test performance?
Track % assets passing Hipot tests and mean time between insulation failures to quantify asset reliability and maintenance effectiveness.