Device and method for detecting disconnection of secondary side of current transformer

Abstract

The invention discloses a device for detecting the disconnection of a secondary side of a current transformer, and the device comprises a sampling circuit which is coupled to the secondary side of thecurrent transformer, so as to achieve the sampling of a signal from the secondary side of the current transformer; a pull-up circuit which responds to a coupling signal when the current transformer is at a diagnosis stage, and is coupled to the sampling circuit in a switchable manner; a processor which is coupled to the sampling circuit so as to receive the sampling signal from the sampling circuit, wherein the processor extracts the corresponding signal information from the sampling signal, and the extracted signal information is corresponding to the connection or disconnection state of thesecondary side of the current transformer and a load when the current transformer is at a correction stage; a storage unit which is coupled to the processor and is used for storing the extracted signal information; and a detector which is coupled to the processor and the storage unit, wherein the detector visits the storage unit through the signal information of the sampling signal at the diagnosis stage, so as to determine whether the extracted signal information is matched with the stored signal information or not, so as to judge whether a load is disconnected from the current transformer ornot.

Description

technical field [0001] The invention relates to a device and method for detecting disconnection of a secondary side of a current transformer. In particular, it relates to a circuit and method for monitoring secondary side voltage to determine if the secondary side is disconnected. Background technique [0002] Current transformers (Current Transformers, CTs) are commonly used in power applications, such as electricity meters. A CT senses the current in the wire and generates a signal proportional to that current. In power applications, the primary current is often too large to be safely measured. CTs can be used to generate a much smaller proportional current on the secondary side, which is suitable to be measured or protected. Since the secondary current is proportional to the primary current, the measured secondary current can be measured by K n =I 1n / I 2n is converted to reflect the primary current, where K n is the primary to secondary current ratio, I 1n is the...

AI Technical Summary

Problems solved by technology

If the secondary side is open circuited, the current in the primary side will push the voltage on the secondary side to a very high value, which will be dangerous and harmful

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