Cable insulation testing

The megohmmeter has three terminals: one is “L”, one is “E”, and the other is “G” (shield). When measuring the insulation resistance of power lines or lighting circuits, “L” is connected to the circuit under test, and “E” is connected to the ground wire. When measuring the insulation resistance of a cable, to obtain accurate results and eliminate measurement errors caused by leakage at the surface of the core’s insulation layer, it is also necessary to connect \"G\" to the cable’s insulating paper. When conducting measurements, the following points should be noted: 1. To measure the insulation resistance of electrical equipment, it is necessary to first cut off the power supply. In the case of devices with capacitive properties, such as cables, the devices must first be discharged. 2. It must be placed flat when in use. 3. Before use, turn it a few times to check whether the pointer is at the maximum position; then short-circuit the two terminals “L” and “E”, and slowly turn the handle to see if the pointer is at the “zero” position. 4. The leads must be well insulated, and the two wires should not be twisted together. 5. When taking measurements, the reading after one minute of rotation should be used as the reference. 6. During measurement, the rotation speed should be brought to 120 revolutions per minute. 7. Its range often reaches several gigaohms, with the smallest scale being around 1 megohm; therefore, it is not suitable for measuring resistances below 100 kohms. Just use it. Connect both ends of the cable to it, then turn the handle on it, and it will be displayed. Clip any two wires from the cable to the two terminals of the megohmmeter, then turn the crank at a rate of about 120 revolutions per minute. The reading on the dial at this point represents the insulation resistance value, which is generally required to be greater than 20 megohms. An insulation meter is used to measure insulation resistance; a digital model is preferred. It seems pretty intuitive. Ground it with the end that has clips (preferably a metal object; grounding is essential)