1_kW_POWER_METER

Published:2009/6/18 23:40:00 Author:May | From:SeekIC

The power meter shown uses only one transistor pair to provide the complete (X)(Y)function.The circuit is intended for 117 Vac±50 Vac operation, but can be easily modified for higher or lower voltages. It measures true (nonreactive)power being delivered to the load and requires no external power supply. Idling power drain is only 0.5W. The load current-sensing voltage is only 10 mV, keep-ing load voltage loss to 0.01%. Rejection of reactive load currents is better than 100:1 for linear loads.Nonlinearity is about 1% full scale when using a 50-μA meter movement. The temperature correction for gain is accomplished by using a copper shunt (+0.32%/℃) for load-current sensing. This circuit measures power on negative cycles only, so it cannot be used on rectifying loads.



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