What are the routine electrical tests for transformers? (Part 1)

Transformers play a central role in power transmission and distribution, and their stable operation is related to the safety of the entire power system. Routine electrical tests are important means to detect the performance of transformers and discover potential faults.

Content

●Voltage ratio test
The voltage ratio test is mainly used to verify whether the voltage ratio of the transformer meets the design requirements. Through this test, it can be detected whether there are short circuits between turns or layers of the winding and whether the switch leads are wrongly connected. In actual operation, accurately measuring the voltage ratio between different windings can timely discover potential electrical connection problems and ensure the normal voltage transformation function of the transformer.

●Winding resistance measurement
The winding resistance measurement can judge the welding quality of the wire and detect whether there are faults such as short circuits in the winding, poor switch contact or wrongly connected leads. Accurately measuring the winding resistance can reflect the conductive performance of the winding, which is of great significance for discovering potential short circuit or poor contact problems. By measuring and comparing the winding resistance at different positions, the fault location can be quickly located and the fault removal efficiency can be improved.

●Insulation resistance and absorption ratio or polarization index measurement
Use a 2500V megger to measure the insulation resistance R at 60 seconds and compare it with the insulation resistance Rs at 15 seconds to obtain the insulation resistance and absorption ratio Ro/R₁s or polarization index. This is a sensitive indicator for judging the insulation deterioration and moisture absorption degree of the transformer. This test can detect the performance of the insulation material of the transformer. By comparing the insulation resistance values at different time points, it can be judged whether the insulation material is aged or moistened. At the same time, the local defects or moisture absorption of insulation cardboard, bushings and windings can also be represented by the ratio.

In Summary

In conclusion, the routine electrical tests of transformers cover multiple aspects, including voltage ratio test, winding resistance measurement, insulation resistance and absorption ratio or polarization index measurement, tanδ measurement, oil test, withstand voltage test, no-load and load tests, etc. These tests cooperate with each other to comprehensively detect the performance and reliability of the transformer, timely discover potential faults and defects, and provide strong guarantee for the safe operation of the transformer.

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LuShan, est.1975, is a Chinese professional manufacturer specializing in power transformers and reactors for 49 years. Leading products are single-phase transformer, three-phase isolation transformers,electrical transformer,distribution transformer, step down and step up transformer, low voltage transformer, high voltage transformer, control transformer, toroidal transformer, R-core transformer;DC inductors, AC reactors, filtering reactor, line and load reactor, chokes, filtering reactor, and intermediate,high-frequency products.

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