Current rating verification system

Abstract

Method and apparatus for verifying the load rating of an active alternating current distribution circuit at a power outlet. The load rating of the distribution circuit is verified by measuring the change in line voltage at the power outlet as different loads are applied. The no-load line voltage is factored out by summing an analog signal derived from the no-load line voltage with a reference voltage to produce a null balance. When the distribution circuit is loaded by a programmed load or by the load of an external appliance such as a resistance heater, the loaded circuit waveform is transformed and rectified to produce a relatively low amplitude no-load direct current waveform. The transformed, loaded circuit waveform and the null balance waveform are summed, amplified and measured. The amplified sum corresponds exactly with the drop in line voltage across the distribution circuit at the power outlet. The value of the measured change is then compared with the specifications of the National Electrical Code to determine the electrical quality of the distribution circuit. Because this value is independent with respect to wire size, wire type or load current, the tester can be used to set an external flag indicating that the voltage drop is greater than the code limit.

Dependencies are inferred from the claim text.