Importance

Loading Importance Indicators...

Abstract

This invention relates to a nulling current transformer. More particularly, this invention relates to a nulling current transformer for accurately detecting current and giving an improved response, accuracy and stability using toroidal current transformer technology along with active components. This invention finds particular application in switchgear devices such as residual current devices and metering operations. The nulling current transformer is implemented in a closed magnetic core having at least one primary winding inductively coupled thereto. A secondary winding is also inductively coupled to said magnetic core, the secondary winding being responsive to any magnetic flux generated in said magnetic core. A separate tertiary winding is also inductively coupled to said magnetic core, the tertiary winding being responsive to any magnetic flux generated in the magnetic core. A nulling means is also provided for receiving the output of said tertiary winding and nulling the received output, the nulled output of the nulling means being connected to the input of said secondary winding such that it serves to cancel the magnetic flux in the magnetic core.

Loading the Abstract Image...

First Claim