Polarity tester for current transformer at transformer neutral point

Abstract

The invention relates to a polarity tester for a current transformer at a transformer neutral point. The tester is internally provided with four terminals, a pointer type DC current milliampere meter A and a test button, and is externally provided with four test wires; a forward 220V DC voltage can be output between a positive primary terminal and a negative primary output terminal; the other two terminals are secondary output terminals; the internal positive primary terminal of the tester is connected with a primary test wires; the negative primary output terminal is connected with one terminal of the test button, and the other terminal of the test button is connected with the other primary test wire; and the two secondary output terminals are connected with an anode and a cathode of the pointer type DC ammeter respectively and are connected with the two secondary test wires at the same time. The tester can accurately check the polarity of the TA secondary winding of the transformer neutral point, avoids incorrect access during connection, improves the operation reliability of a transformer, and ensures the stable operation of a power system.

Description

technical field [0001] The invention relates to a polarity testing instrument for a neutral point current transformer of a transformer, which belongs to the field of electric system relay protection and safety automatic device inspection. Background technique [0002] The substation is the power supply hub of the power system, and it supplies power to users through the transformer in the substation. Transformer neutral point current transformer (transformer neutral point TA for short) is actually a kind of current transformer. The function of current transformer is to convert large current (primary current) into small current (secondary current). The transformer neutral point TA is installed between the transformer bushing and the transformer neutral point grounding disconnector. That is, the upper end (polar end) of the transformer neutral point TA is connected to the non-polar end of the transformer bushing inside the transformer, and the lower end (non-polar end) is conn...

AI Technical Summary

Problems solved by technology

In fact, this approach is very one-sided. It is equivalent to not doing a polarity check test after the secondary connection of the transformer. Once there is a problem with the secondary polarity, it will also cause the following two hazards: (1) When the transformer has a ground fault (2) When a ground fault occurs in the transformer, the faulty transformer cannot be tripped and shut down, causing damage to the faulty transformer

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