Capacitance and Dielectric Loss Measurement

Capacitance and dielectric loss measurement

-Test purposes of Capacitance and Tan Delta

The purpose of measuring dielectric loss is to determine the insulation status of electrical equipment. Measuring dielectric loss factor is an indispensable item in preventive tests. Because the dielectric loss factor of the electrical equipment is too large, the equipment insulation will be lost in the form of heat under the action of AC voltage. The generated heat will increase the temperature of the insulation of the electrical equipment, make the insulation aging, and even cause insulation thermal breakdown. The decrease in insulation capacity is directly reflected as the increase in dielectric loss factor. Further, the reasons for the insulation degradation can be analyzed, such as: insulation moisture, insulation oil contamination, aging deterioration, and so on. Therefore, the dielectric loss test should be carried out during the factory test, and the electrical equipment in operation should also be subjected to this kind of test. While measuring the dielectric loss, the capacitance of the sample can also be obtained. The obvious change in capacitance reflects the short circuit or open circuit of one or several of the multiple capacitors.

-Principle of Tan Delta Test

Dielectric loss is the energy loss caused by the insulating material under the action of an electric field due to the hysteresis effect of dielectric conductivity and dielectric polarization. Also called dielectric loss, referred to as dielectric loss.

Under the action of AC voltage, the angle between the current phasor and the voltage phasor flowing in the dielectric is the power factor angle (Φ), and the complementary angle (δ) is referred to as the dielectric loss angle.

Dielectric loss tangent δ

tg, also known as dielectric loss factor, refers to the dielectric loss tangent value, referred to as dielectric loss tangent.

Dielectric loss factor (δ

The measurement of tg) is indispensable in the manufacture of electrical equipment, the appraisal of the electrical properties of insulating materials, and the test of insulation. Because measuring the δ of the insulating medium

The tg value is a more sensitive test method for judging the insulation condition. Under the action of AC voltage, the insulating medium not only has conductivity loss, but also polarization loss.

The cable, winding, current transformer, potential transformer, transformer bushing, on which tan delta test or dissipation factor test to be conducted, is first isolated from the system. A very low-frequency test voltage is applied across the equipment whose insulation to be tested.

More details on Transformer Capacitance & Tan Delta Tester, Capacitance & Dissipation Factor Testing Equipment, C&DF Tester, please contact EP Hipot Electric Co., Ltd. yingying@ephipot.com.