Insulation Resistance Tester, commonly known as "megohmmeter" or "megger", is one of the most basic and important instruments in electrical safety testing and preventive maintenance. It is used to measure the insulation resistance of electrical equipment, cables, motor windings, etc., to determine whether the insulation material is damp, aged, dirty, or has penetrating defects. In the technological context of 2026, traditional mechanical meggers have been almost completely replaced by high-precision digital intelligent insulation resistance testers, with more integrated and intelligent functions. 1. Core Working Principle: Basic Principle: The instrument internally generates a stable high-voltage DC power supply (such as 500V, 1000V, 2500V, 5000V, 10000V, etc.), applied between the conductor of the object under test and ground (or another conductor). Application of Ohm's Law: It measures the weak leakage current flowing through the insulation medium (usually at the nA or μA level), according to
