Zero-flux micro-current sensor used for leakage current detection

Abstract

A zero-flux micro-current sensor used for leakage current detection includes a main magnetic core, an auxiliary magnetic core, a secondary winding a detection winding, a compensation winding, a signal processing circuit, an active compensation circuit and a passive compensation circuit; the zero-flux micro-current sensor is characterized in that one ends of the main magnetic core and the auxiliary magnetic core are uniformly wound by the secondary winding, and the output end of the secondary winding is connected with the signal processing circuit; the other ends of the main magnetic core and the auxiliary magnetic core are uniformly wound by the detection winding and the compensation winding; and the detection winding and the compensation winding are connected through the active compensation circuit, and the passive compensation circuit is connected to the detection winding in parallel. According to the zero-flux micro-current sensor used for leakage current detection, the compensation circuits combines active and passive modes, measurement accuracy of the current sensor is improved, the compensation speed is fast, and the accuracy is high, and after compensation, the current sensor can reach a 0.2 grade in accuracy when measuring microampere- to milliampere-level power frequency currents.

Description

technical field [0001] The invention relates to a micro-current sensor, in particular to a zero-flux micro-current sensor for measuring power frequency μA-mA level alternating current. Background technique [0002] Nowadays, current transformers with single-turn core-through structure are commonly used in power systems as micro-current sensors, so that the original grounding method of power equipment is not changed, and the operation safety of the tested equipment is guaranteed. At the same time, it can also play a high-voltage isolation role for the monitoring system. . [0003] The current sensor realizes energy transfer by the primary side current and the secondary side current through the principle of magnetic induction coupling, and the error affecting the output result is mainly caused by the excitation current required to establish the magnetic flux in the iron core. If the magnetic current is zero, the excitation magnetic potential is 0, and the error is zero. At th...

AI Technical Summary

Problems solved by technology

Usually, the realization method of zero flux technology is divided into two-stage zero-flux structure and single-core structure in structure. Although the "zero-flux" current sensor with single-core structure has a simple structure, its compensation accuracy is lower than that of two-stage zero-flux. structured current sensor

The implementation of the dual-stage zero-flux structure current sensor usually uses a single-chip microcomputer to control the potentiometer to automatically track and compensate the excitation current. Due to the participation of software and A / D conversion errors, it is necessary to use algorithm programs to realize signal conversion, which will slow down the response speed. , the implementation method is complex, so the compensation accuracy is not high when measuring microampere-level power frequency AC

[0005] In the prior art, the application number is CN201510347095.9, which discloses "a zero-flux current transformer test quick wiring device and its use method", including a power conversion module, a DC current generation module, a wiring mode conversion module, and a test line. The power conversion module is connected with the DC current generation module, and the power conversion module is connected with a DC power output plug and an AC power plug, and the DC current generation module is connected with a DC current lead; although it overcomes the complicated and time-consuming wiring of the previous zero-flux CT test , the shortcomings of being limited by the test site, but lack of weak signal processing units, and did not mention the specific compensation scheme based on zero magnetic flux and its positive effects

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