megohmmeterit

A megohmmeter, also known as a megger, is an electrical test instrument used to measure high electrical resistance, typically in the megohm range. It is commonly employed in the testing of insulation resistance in electrical systems, motors, cables, and other high-resistance components. Unlike standard multimeters, which measure resistance in ohms, a megohmmeter is specifically designed to handle the high resistance values found in insulation materials.

The device operates by applying a direct current (DC) voltage, usually between 100 and 1000 volts, across the component being tested. The current that flows through the insulation is then measured, and the resistance is calculated using Ohm’s Law. Most megohmmeters include a built-in power source, such as a hand-cranked generator or a battery, to supply the required test voltage.

Megohmmeters are widely used in industrial maintenance, electrical engineering, and quality control to ensure that insulation remains intact and functional. Proper insulation resistance is critical for preventing electrical leaks, short circuits, and equipment failure. Common applications include testing motors, transformers, switchgear, and power cables before installation or after maintenance.

Modern megohmmeters often feature digital displays and additional functions, such as polarization index (PI) testing, which helps assess the condition of insulation over time. Safety precautions are essential when using a megohmmeter, as the high test voltages can pose a risk of electric shock. Operators should follow manufacturer guidelines and use appropriate protective equipment when conducting tests.