A portable device designed to quickly locate a faulty isolator in the insulator chain in hot distribution and transmission circuits.

Its working principle is based on measuring the potential difference in the tested insulator disc. A high impedance galvanometer indicates this potential difference for comparisons with other isolator discs in the same system. Thus, a defective isolator will show a reading considerably lower than the others.

It can be used to evaluate pin insulators, one piece isolators, multipart pin insulators, and disc insulators.

It is made of fiberglass tubing and housing, with quick and multiangular adjustment of contact tips. The insulator tester is designed to test any insulator measurement and to make other adjustments for better viewing.

The instrument has a 3-position switch on its backside to change sensitivity for a better selection of pointer range.

The calibration device is designed to check the insulator tester before use, especially after a long inactive period.

It generates a digital signal to the insulator to compare the values shown in the calibration display and the insulator tester galvanometer reading.