5-ka zero-track DC (direct current) comparator for calibrating current transformer

Abstract

The invention relates to a 5-kA zero-track DC (Direct Current) comparator for calibrating a current transformer. A primary winding and a secondary winding are wound around a main iron core; an oscillator, a modulation circuit, a demodulation circuit and an amplification driving circuit are sequentially cascaded, the primary winding and the secondary winding are arranged outside a magnetic shield, and the primary winding penetrates out of an inner hole of the magnetic shield; the modulation circuit is formed by respectively winding two modulation detection windings with the same turns on an annular iron core in opposite winding directions; the magnetic shield is wrapped outside the two modulation detection windings, and the two modulation detection windings and the secondary coil of the oscillator are sequentially connected in series; and the demodulation circuit is a passive resistance-capacitance network circuit which is used for demodulating a difference-value signal from the modulation circuit into a DC voltage signal in direct proportion to the difference-value signal. The 5-kA zero-track DC comparator provided by the invention reaches the accuracy degree up to 2*10<-6> and fully meets the requirement for calibrating the DC transformer on site.

Description

technical field [0001] The invention relates to a calibration device for DC output equipment of a DC substation, in particular to a standard calibration device for pre-installation calibration tests and synchronous calibration of DC transformers of primary equipment in a DC power transmission system. Background technique [0002] The DC transformer is an important primary equipment of the DC transmission system. It provides accurate and reliable measurement information for the control and protection of the system. The pre-installation verification test and periodic calibration of the DC transformer equipment used in the system is to ensure the safe operation of the DC transmission system. indispensable work. [0003] Existing calibration equipment such as the magnetic modulation DC comparator was first successfully developed by Kusters in Canada in the 1960s, and its accuracy is as high as 1×10 -6 Above, countries all over the world have adopted this DC current comparator a...

AI Technical Summary

Problems solved by technology

For example, the on-site injection test of DC current transformers was generally carried out at 10% of the rated current in the past, and the on-site injection pressure test of the pole-line DC voltage divider was carried out at 10% of the rated voltage, and only a rough inspection of the transformation ratio was carried out. The on-site calibration test of the DC measuring equipment of the flow station under the rated conditions has always been a blank

Images