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Detection Technology

Principle and method of deformed winding tester

time:2021/2/7   source:华天电力  reading:243 time

Using frequency response analysis to detect transformer winding deformation is to detect the amplitude-frequency response characteristics of each winding of the transformer, and compare the detection results longitudinally or laterally, and determine the possible winding deformation of the transformer based on the difference in amplitude-frequency response characteristics.

The amplitude-frequency response characteristics of the transformer windings are obtained by frequency sweeping, continuously changing the frequency f of the external sine wave excitation source VS (angular frequency ω=2πf), and measuring the response terminal voltage V2 and excitation terminal voltage V1 signals at different frequencies The ratio of the amplitudes to obtain the amplitude-frequency response curve of the winding under the conditions of the specified excitation end and response end.

Sweep Frequency Response Analyzer.png

Detection method: The transformer winding deformation detection should be performed before all DC test items or after the windings are fully discharged. The transformer windings should be tested one by one according to the wiring requirements and wiring methods, and the amplitude-frequency response characteristic curves should be recorded separately.

Wiring requirements: All leads connected to the end of the transformer bushing should be removed before testing, and the removed lead should be as far away as possible from the tested transformer bushing. For transformers whose bushing leads cannot be removed, the end screen tap of the bushing can be used as a response The test should be carried out at the end, but it should be noted and should be compared with the test results under the same conditions.

The amplitude-frequency response characteristics of the transformer windings are related to the position of the tap changer. It should be tested in a high tap position, or the tap changer should be in the same position for each test. Because the detection signal is weak, all connections should be stable , Reliable, reduce contact resistance.

The grounding wires of the two signal detection terminals should be reliably connected to the obvious grounding terminal (such as the iron core grounding terminal) on the transformer shell. The grounding wire should be as short as possible and should not be twisted.

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