Insulation resistance meters are specialized measuring instruments used to test the insulation performance of electrical equipment and machinery in manufacturing facilities. Essential for insulation deterioration diagnosis and preventive maintenance of motors, transformers, switchboards, control panels, cables, electric furnaces, and other equipment, these devices are also known as meggers or teraohm meters. Mainstream products comply with JIS C 1302 standards, featuring measurement voltages from 250V to 5000V and measurement ranges from 0.01MΩ to 10TΩ. Available in digital display, analog pointer, and data logger-equipped models to suit various applications. Used for periodic inspections based on electrical safety regulations in manufacturing, completion inspections during equipment installation, and insulation diagnosis during troubleshooting. These instruments differ clearly from general voltage/current meters and multimeters in both measurement principles and applications.