Insulation resistance monitor checking device - with monitor bridge amplifier input switching between insulation and test resistances

摘要

An electrical device checks the operation of an electrical monitor for the isolation resistances of a unit supplied with d.c., esp. a signalling or data terminal, which has a four-arm measurement bridge. One arm contains an insulation resistance, another a balancing potentiometer, and a measurement amplifier is connected across the bridge diagonal. It permits reliable testing of the resistance and the leads connecting it the unit. The amplifier, which drives an indication signal generator, has inputs switched between the insulation and a test resistor by a pulsed switch.