The M-500 is an automatic, portable, battery-powered insulation tester. This unit is specifically designed as an inexpensive alternative to costly swing needle megohmmeters. The M-500 measures insulation resistance values of motors, generators and transformers up to 1000 megohms at 500VAC, indicating the condition of insulation on the zone scale. Its compact design and ease of use makes the M-500 a great diagnostic tool for motor rewind shops, electrical maintenance personnel and pump installers.