Dielectric loss tester, abbreviated as dielectric loss meter, full name dielectric loss tester



is a precision automated instrument specifically used to measure the dielectric loss tangent (tgδ or tanδ) and capacitance (Cx) of insulating materials in high-voltage power equipment.

It is mainly used to evaluate the insulation performance of high-voltage equipment such as transformers, instrument transformers, bushings, and power cables, and to determine whether they are damp, aged, or deteriorated.

⚙️ Core Working Principle

The core principle of the dielectric loss tester is based on vector operations under an AC electric field:

Dielectric loss tangent (tgδ): Under the action of AC voltage, the insulating medium consumes part of the electrical energy and converts it into heat. The instrument calculates the tangent of the dielectric loss angle (tgδ) by measuring the phase angle difference between voltage and current. The smaller the value, the lower the energy loss of the insulating material and the better the insulation performance.

Digital measurement: Modern dielectric loss testers contain a standard circuit (with a built-in high-stability standard capacitor) and a test circuit. The instrument uses high-speed sampling circuits to measure the current amplitude and phase difference of the two circuits respectively, and then uses a digital signal processor (DSP) for vector operations to ultimately obtain the tgδ value and capacitance value of the test object.