Abstract: This invention relates to a method and apparatus for executing secondary functions on an electrical switchgear device. In particular, the present invention relates to a method and apparatus which is implemented in the processing electronics of an electrical switchgear device which has a primary trip or protection function and also the capability to execute secondary functions or applications, such as over/undervoltage conditions and near fault warning levels and display. These secondary functions or applications being user configurable and are subject to processing availability and the constraints of the primary protection function.

Abstract: A three-dimensional circuit substrate comprises one or more electrically conductive tracks. The substrate is formed from a unitary moulding over the one or more electrically conductive tracks and thereby provides structural support therefor.

Abstract: A method of forming an electrical circuit for an electrical component comprises the steps of; producing an electrical circuit from a planar conductive material, the circuit including tracks and tie bars between tracks; over-moulding the electrical circuit ith plastics material leaving tie bars in apertures; and removing the tie bars after the over-moulding process.

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.

Abstract: This invention relates to a residual current device which is able to safely and reliably operate when a line voltage is present (voltage dependent mode) and when the line voltage is not present or falls below a predetermined threshold level (voltage independent mode). The present invention is implemented as a residual current device having a trip mechanism for isolating an electric supply to an electrical installation upon detection of a predetermined current imbalance between the line and neutral conductors of said electric supply. The present invention comprises a current transformer having a secondary winding responsive to any current imbalance on said electrical installation, and a circuit protection winding being connectable to a processing means.