Current diagnosing device and method for monitoring state of current transformer

Abstract

A current diagnosing device for monitoring the state of a current transformer comprises a state-detecting grounded resistor which is arranged between an output end of a secondary coil of the transformer and a signal-regulating circuit and one end of the state-detecting grounded resistor is grounded. The signal-regulating circuit connected between analog digital (AD) pins of the transformer and a central processing unit is a proportional integral circuit and is used for converting a main circuit current signal output by the current transformer into an alternating voltage signal and regulating the amplitude and phase of the signal. The central processing unit performs the AD conversion on the voltage signal output by the signal-regulating circuit. When the circuit of the current transformer is broken, the signal-regulating circuit outputs a fixed direct-current voltage signal which surpasses a set threshold value deviating from the reference voltage Vref. When the value of the counter reaches the preset period and the average values of all periods surpass the threshold value, the central processing unit gives a failure warning and instructs a tripping driving unit to drive a breaker to do disconnecting operation and the display unit displays the current and failure information of the main circuit.

Description

technical field [0001] The invention relates to a current diagnostic device for a current transformer of a circuit breaker, in particular to a current diagnostic device and a diagnostic method for monitoring the working state of the current transformer of an intelligent circuit breaker. Background technique [0002] With the continuous deepening of the country's intelligent transformation of the power grid, higher requirements are placed on the reliability of the equipment used in the power grid. As far as the circuit breaker is concerned, it is an important device to ensure the safety of the back-end electrical equipment and personal safety, and the importance of its working reliability can be imagined. The hollow coil type current transformer is a commonly used component to detect the current in the main circuit of the circuit breaker. Its working principle is to use the main circuit controlled by the circuit breaker as the primary winding of the current transformer, and t...

AI Technical Summary

Problems solved by technology

The defect of the above existing technologies is that an external signal must be introduced into the current transformer, which will directly affect the sampling signal of the current transformer and cause distortion of the current sampling, so calibration measures must be taken at the back end for correction, such as US20070063797A1 A proofreading link is added to the software to remove the DC voltage signal to restore the real current sampling signal

However, this method increases the signal processing steps, which not only reduces the accuracy of current sampling, but also leads to complex methods and structures, and increases manufacturing costs.

Images