Conduct regular insulation preventive tests on electrical equipment, which can promptly discover the local defects left by the equipment insulation materials or generated during operation, facilitate the understanding of the operating status of the electrical equipment and the integrity of the insulation, and determine whether the electrical equipment can continue to be put into operation and prevent Damage, so that the equipment always maintain a higher insulation level. It is an important work to ensure the reliable operation of electrical equipment insulation and the safe operation of substations.

The so-called insulation resistance is the ratio of the applied DC voltage to the steady-state current when the current in the insulating medium decays with time and finally reaches stability under the action of the DC voltage. Insulation resistance can reflect the insulation state of electrical equipment to a certain extent (such as the moisture content of the insulating medium and the cleanliness of the surface). Insulation resistance is greatly affected by temperature and humidity and should be measured when the weather is fine.

Resistance tester is an indispensable electronic equipment tool for electrical safety inspection and grounding project completion acceptance. Including ground resistance tester, insulation resistance tester, ground resistance tester, DC resistance tester, surface resistance tester and loop resistance tester. The grounding resistance tester refers to the resistance of the grounding body buried in the ground and the resistance of the soil dissipating current, and it is usually measured by a grounding resistance meter (or ground resistance shaker). The shape of the type measuring instrument is similar to that of an ordinary insulation shaker, and it is also called a grounding resistance shaker according to custom. The appearance and structure of the model shake meter vary slightly with the model, but the usage method is basically the same. The grounding resistance measuring instrument comes with two grounding probes and three wires.