Potential-less current measurer suitable for monitoring and protection - comprises magnetic field ring sensor with substrate having central opening for current conductor

摘要

The current measurer has a circular central aperture to accommodate a current conductor. The ring sensor (4) is formed from ferromagnetic, single element, magnetic field sensors (5) with their magnetism set vertically to the direction of the circumference of the conductor and is based on the magneto-resistance effect. The sensors are connected in series and are set radially or axially w.r.t. the conductor. The sensors can be additionally magnetised by a circular pre-magnetising coil with an iron core arranged around the conductor. The useful magnetic field arising from the current flowing through the conductor causes the ohmic resistance of the ring sensor to change. This is evaluated for use as a current measuring signal. USE/ADVANTAGE - Monitoring and appts. protection for electronics, drives and l.v. power applications. Can be used in magnetically ''raw'' environment i.e. where interference from foreign magnetic fields can be encountered. Suitable for miniaturisation.