Insulators are designed to isolate electrical conductors from one another. An insulator should have high resistance to current and high breakdown voltage. However, moisture, salt and pollutants can create conductive paths which can cause flash overs or arcing. Insulation testers help determine if an insulator’s resistivity is decreasing.
An insulation tester helps determine the condition of the insulator by measuring its resistance. One of the widely used testers is the MI 3200 TERAOHM from Metrel. It has a variable output test voltage ranging from 500 volts to 10 kilovolts with 25 volts increments. MI 3200 has an auto-calibration of the measuring system and can measure resistances of up to 10 terraohms. It can be operated using its internal rechargeable battery or through AC power. This tester has a system that automatically discharges capacitive loads after the test. This feature helps prevent stored current to damage other electrical equipment or shock personnel.
If you need to test insulators in your electrical facility but don’t have the right equipment, you can rent from