Insulation resistance tester is more commonly referred to as a megohmmeter in the power industry



Older electricians also habitually call it a "megger".

If the dielectric loss tester we discussed earlier is like a precise "MRI" for power equipment, then the insulation resistance tester is the most basic and critical "insulation withstand voltage physical examination" for equipment. Its core task is very simple and direct: apply a high voltage to electrical equipment to see if its insulation layer "leaks", thereby determining whether the equipment can be safely energized and operated.

⚙️ Core Uses and Importance

In power systems, the insulation performance of equipment such as transformers, generators, high-voltage motors, and power cables directly relates to the safety of personnel and equipment.

Core function: By measuring the insulation resistance value of these devices under high voltage (usually in megohms MΩ or gigohms GΩ), it detects whether the insulation is damp, aged, dirty, or at risk of breakdown or short circuit.

Wide application: It is the most frequently used "entry-level" mandatory test item in power equipment maintenance, installation acceptance, and routine preventive tests.