The instruments used to measure insulation resistance are:
1. The megohmmeter is mainly used to check the insulation resistance of electrical equipment, household appliances or electrical circuits to the ground and between phases. According to different products, the megohmmeter selects different voltage levels such as 100V, 250V, 500V, 1000V, etc., to measure its insulation resistance value.
2. The multimeter can be used to measure the resistance value of the equipment components. When measuring the insulation resistance of the multimeter, it should be adjusted to the ohm range for measurement, generally: x1, x10, x100, x1000.
The digital megohmmeter is composed of medium and large-scale integrated circuits. This watch has large output power, high short-circuit current value, and multiple output voltage levels. The working principle is that the DC high voltage generated by the internal battery as the power source through the DC/DC conversion passes from the E pole to the L pole through the tested product, thereby generating a current from E to L pole, which is completed by the divider through the I/V conversion. The calculation directly displays the measured insulation resistance value on the LCD.
The basic principle of a multimeter is to use a sensitive magnetoelectric DC ammeter (micro-ammeter) as the meter head. When a small current passes through the meter, there will be a current indication. However, the meter head cannot pass large currents. Therefore, some resistors in parallel and series must be connected to the meter head to shunt or step down, so as to measure the current, voltage and resistance in the circuit.