Wuhan UHV specializes in producingseries resonance (also known as power frequency withstand voltage test device). Next, we will share the difference between induction withstand voltage and power frequency withstand voltage.

In the power system, induction withstand voltage is an important functional test to assess the insulation strength of electrical equipment such as transformers, reactors, and voltage transformers. In DL/T474.4-2006 "Guidelines for the Implementation of On site Insulation Tests", it is clearly stipulated that in addition to the main insulation, transformers should also undergo insulation performance tests for longitudinal insulation such as turns, layers, and breaks, which can effectively check the integrity of winding coils!

Induction voltage withstand test method

Inductive withstand voltage is different from power frequency withstand voltage. Power frequency withstand voltage applies high-frequency high voltage on the primary side, while inductive withstand voltage applies multiple times higher than the rated voltage on the low-voltage side of a transformer or transformer. It relies on the electromagnetic induction of the transformer itself to obtain the required test voltage on the high-voltage winding to test the longitudinal insulation performance of the transformer, especially for transformers with neutral point graded insulation. Since external high voltage cannot be used for power frequency AC withstand voltage test, both the main insulation and longitudinal insulation are evaluated by inductive withstand voltage test. The measurement of inductive withstand voltage should be carried out using electronic multiple frequency generators that comply with national standards or simplified versions of three frequency power generators.

The difference between induction withstand voltage and power frequency withstand voltage

The power frequency AC withstand voltage test only checks the electrical strength of the main insulation of the winding, that is, the insulation between the high voltage, medium voltage, and low voltage windings and the grounding parts of the oil tank, iron core, shell, etc., while the induction withstand voltage test checks the insulation performance of the longitudinal insulation between turns, layers, breaks, etc. They complement each other but cannot replace each other.

Inductive voltage resistance has the following functions

(1) Assess the longitudinal insulation of fully insulated transformers, semi insulated transformers, and fully insulated transformers; (2) Assess the partial main insulation and longitudinal insulation of graded insulation transformers.