Differential current measuring apparatus, tripping device and switchgear

摘要

The device has a magnetic core (16) surrounding current lines (25) and forming a primary transformer circuit, and a secondary winding (11) wound around the magnetic core and forming a secondary transformer circuit. A metallic sheeting surrounds the secondary winding and the magnetic core. Another secondary winding (2) surrounding the sheeting constitutes a magnetic circuit of a current sensor providing electrical signal representing a current circulating in a current line. An independent claim is also included for a switchgear for protecting electrical lines and comprising a triggering module.