Direct-current attenuation variable-frequency demagnetizing device

Abstract

The invention provides a device which is used for eliminating and measuring residual magnet of a large-capacity high-voltage large-sensing electrical device of an electric power system. An innovative direct-current attenuation variable-frequency technology is adopted to produce a direct-current attenuation variable-frequency signal to demagnetize a high-voltage end of a mutual inductor and a power transformer; and simultaneously an alternative-current signal is applied to a low-voltage end of the mutual inductor and the power transformer to measure the residual magnet through a particular method. The direct-current attenuation variable-frequency demagnetizing device achieves a small size, a light weight, thorough demagnetization, rapidness in demagnetization, simpleness in measurement of residual magnet and the like. The weaknesses of an alternative-current method such as large size, heavy weight, inconvenience for on-site application, complicated structure and complexity in operation can be overcome, the effect of the alternative-current method is achieved, and the residual magnet is quantitatively measured. The safe and normal running of the power equipment can be guaranteed, and the national economic benefit can be further improved.

Description

technical field [0001] The invention belongs to the technical field of electric power system inductive equipment, and relates to a large-capacity, high-voltage, high-inductance electrical equipment for the elimination of residual magnetism and the measurement of residual magnetism, in particular to a kind of residual magnetism after measuring the DC resistance of a power transformer and transformer Elimination and measurement of residual magnetism. Background technique [0002] Due to the inherent hysteresis of ferromagnetic materials, residual magnetism will remain in the iron core after performing voltage ratio and DC resistance measurements on power transformer transformers. Due to the existence of residual magnetism, when the transformer is put into operation, the residual magnetism of the core will saturate the transformer core for half a cycle, resulting in a large amount of excitation current, and the excitation current will carry a large number of harmonics. This no...

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Problems solved by technology

[0003] 1. Causes the relay protection device of the transformer to malfunction, causing frequent failures in the operation of the transformer;

[0004] 2. The voltage surge generated when the short-circuit fault of the transformer outgoing line is removed, which induces the malfunction of the transformer protection and causes all the loads on each side of the transformer to be cut off;

[0005] 3. The excitation inrush current generated by a transformer in A power station connected to the power supply without load induces the "sympathetic inrush" (sympathetic inrush) of the operating transformers in other neighboring power stations B and C, which cause a large-scale power outage;

[0006] 4. The excitation inrush current with a large value will cause damage to the transformer and circuit breaker due to excessive electromotive force;

[0007] 5. Induce control overvoltage and damage electrical equipment in the power grid;

[0008] 6. The DC component in the excitation inrush current causes the magnetic circuit of the current transformer to be over-magnetized, which greatly reduces the measurement accuracy and the correct action rate of the relay protection device;

However, the AC degaussing equipment is only suitable for transformer and transformer manufacturers to use in the laboratory, because it is huge and heavy, it is not suitable for field application, the composition is complicated, and the operation is cumbersome.

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