EXTECH MG500 [13/15] Insulator measurement considerations

MG500-en-GB_v1.3 3/17

Insulator Measurement Considerations

Insulators may get contaminated over time from a mixture of dust and moisture. Dust and

moisture problems lower the resistance of the insulator as this resistance is in parallel with the

insulator resistance. It is recommended that the insulator be measured first without the optional

guard lead, to verify that the total resistance is high. Should the total resistance not be high

enough, the contaminants should be removed or the insulator replaced. Test the dirty insulator

for proper resistance by testing with the optional guard lead. Note: If cleaning the insulator is

possible, follow the procedure of the manufacturer.

DIRTY INSULATOR

ELECTRICAL EQUIVALENT

CIRCUIT DIRTY INSULATOR

TYPICAL TEST

Notes:

Resistance as a result of contamination can lower the total resistance.

Cleaning periodically can reduce system power consumption.