When electrical equipment and appliances are working, they will be subjected to overvoltages from inside and outside that are much higher than the normal rated working voltage, resulting in defects in the insulation structure of electrical equipment and latent faults.

In order to timely discover hidden dangers of insulation of equipment in operation and prevent accidents or equipment damage, a series of test items for inspection, testing or monitoring of equipment are collectively referred to as preventive testing of electrical equipment. Preventive testing of electrical equipment also includes testing of oil or gas samples.

Preventive testing is an important link in the operation and maintenance of electrical equipment, and one of the effective means to ensure the safe operation of electrical equipment. So, how are preventive trials classified? What relevant regulations should be followed in conducting preventive testing programs? What qualities should technicians engaged in electrical preventive test projects have? This article will combine the above problems, HV Hipot will systematically describe the relevant knowledge of the preventive test of electrical equipment for everyone.

The significance of preventive trials

Because there may be some quality problems in the design and manufacturing process of power equipment, and it may also be damaged during installation and transportation, which will cause some latent failures. During the operation of power equipment, due to the influence of voltage, heat, chemical, mechanical vibration and other factors, its insulation performance will crack, or even lose insulation performance, resulting in accidents.

According to relevant statistical analysis, more than 60% of power outage accidents in the power system are caused by equipment insulation defects.

Insulation defects of power equipment are divided into two categories:

One is concentrated defects, such as partial discharge, partial moisture, aging, partial mechanical damage;

The second type is distributed defects, such as the overall insulation moisture, aging, deterioration and so on. The existence of insulation defects will inevitably lead to changes in insulation properties.