Controlled auxiliary power supply for electricity meter testing - supplies intrinsic meter voltage path loads avoiding reduction in measurement accuracy

摘要

A controlled auxiliary power source for meter testing contains a difference current sensor (1) which produces a signal proportional to the difference of the controlled signal. A very high gain amplifier (6), whose output is connected to a control current input, has the meter voltage path (15) between its output ports (7,8). The difference current sensor is a difference current counter inductance. The load on the amplifier is relieved by connection to a constant current source (16). ADVANTAGE - Auxiliary sources are used to ensure that currents required to supply intrinsic voltage path loads do not flow through meter current paths and degrade measurement accuracy.