The tangent value of dielectric loss angle is also called dielectric loss factor or dielectric loss for short. Measuring the dielectric loss factor is a highly sensitive test item, which can find the overall insulation of power equipment is affected with damp, deterioration and deterioration, as well as the local defects of small volume tested equipment that are connected or not connected. For the same equipment, the insulation is good, the active component of the current passing through is very small, and the dielectric loss is also very small, Tan5 is very small, otherwise, it will increase, so the state of the insulating medium can be judged by measuring the tangent value of the dielectric loss angle
Due to the high sensitivity of measuring dielectric loss factor to reflect the above defects, it has been widely used in electrical manufacturing, power equipment handover and preventive tests. The Specification for Dielectric Loss Testing of Electrical Equipment such as Transformers, Generators and Circuit Breakers has been stipulated.