Insulation Resistance Tester is often called a Megohmmeter in the electrical field



Insulation Resistance Tester, often referred to as a Megohmmeter, digital insulation tester, or insulation meter in the electrical field, is an electronic instrument specifically designed to measure the insulation resistance of electrical equipment, power lines, and materials.

It is an essential testing tool for ensuring electrical safety, preventing electrical fires, and equipment failures, and is widely used in fields such as power, communication, electromechanical installation, petrochemical, and railway transportation.

⚙️ Core Functions and Working Principle

Basic working principle: Based on Ohm's law (R = U / I). The instrument internally generates a stable high DC voltage (such as 500V, 1000V, 2500V, etc.) through electronic circuits, applies it to the object under test, and then measures the weak leakage current flowing through the insulating material, thereby accurately calculating the insulation resistance value (usually in megohms MΩ or gigohms GΩ).

Core testing functions:

Insulation resistance measurement: Directly read the insulation resistance value of the equipment under high voltage to determine whether its insulation performance meets the standards.

Absorption ratio (DAR) and polarization index (PI): Modern intelligent testers can automatically calculate the resistance ratio of 60s/15s (absorption ratio) or 10min/1min (polarization index). These two indicators can more deeply reflect the moisture and aging conditions of insulation materials in large equipment (such as transformers and generators).

AC/DC voltage measurement: Many devices also have multimeter functions to detect whether the line is live, preventing dangerous live testing.