Digital sampling laboratory wattmeter

A versatile laboratory multifunction wattmeter based on digital sampling has been developed for incorporation into a laboratory calibration system. The meter uses two 15-bit analog-to-digital converters and achieves an overall power measurement accuracy of 0.015% of applied volt-amperes at power line frequencies over the range of 100 mA to 100 A and 5-100 V. Although intended for system use through the IEEE standard 488 bus, the meter can be used as a standalone instrument if required.