Detection device for circuit breakage and short circuit of secondary coil of electric leakage mutual inductor

Abstract

The invention discloses a detection device for circuit breakage and short circuit of a secondary coil of an electric leakage mutual inductor. The detection device comprises a residual current signal detection module, an operational amplifier module and a main control module, wherein the residual current signal detection module is used for detecting the operational amplifier module; the operational amplifier module is connected with the main control module; a sampling resistor in the residual current signal detection module is adopted to sample a present value of a direct-current voltage component according to the Ohm's law; the operational amplifier module is used for amplifying the direct-current voltage component; the main control module is used for judging the present state of the secondary coil of the leaking mutual inductor by calculating the amplified value of the direct-current voltage component; the sampling resistor in the residual current signal detection module is used for converting present alternative-current of the leaking mutual inductor into an alternative-current voltage component; the operational amplifier module is used for amplifying the alternative-current component; the main control module is used for calculating an external residual current value according to the alternative-current component and the resistance of the sampling resistor R1. By adopting the detection device, the circuit breakage and short circuit faults of the secondary coil of the leaking mutual inductor can be easily and effectively detected, and the external residual current value can be normally measured.

Description

technical field [0001] The invention relates to the technical field of detection of electrical fire monitoring systems, in particular to a detection device for open circuit and short circuit of a leakage transformer secondary coil. Background technique [0002] Leakage transformers are important components in power systems. When the leakage transformer is disconnected, a high induced voltage will be generated, which will cause damage to equipment and people. Therefore, it is often necessary to detect the disconnection of the leakage transformer in time so that the relay protection equipment can take protective measures. There are two commonly used disconnection detection methods for the leakage detection of the secondary coil of the leakage transformer: one is to add an additional detection loop to the primary loop of the leakage transformer, and the loop passes through the induction coil of the leakage transformer. Artificially applying a current change will cause an indu...

AI Technical Summary

Problems solved by technology

Although the former method can detect broken wires, when the rated current of the leakage transformer is very large, when it is desired to detect a reliable current for the second time, the artificially applied current is very large, which increases the cost and complexity of the system ; The latter method needs to add a load disconnection detection current module in the secondary coil circuit. Although the cost of the system is reduced to a certain extent, it does not reduce the complexity of the entire system. The additional load disconnection detection current module also means Significantly reduces the reliability and ease of production of the entire system

Moreover, the above two methods can only detect whether the leakage transformer is in a disconnected state, and cannot accurately detect whether the leakage transformer is in a short circuit state, and there is no way to measure the external residual current value while detecting the current state of the leakage transformer

Images