The Digital Multifunction Power Measuring System

The Digital Multifunction Power Measuring System is the outgrowth of a project involving the design of a prototype precision Digital Watt Transducer for the Bonneville Power Administration (BPA). A prototype Digital Watt Transducer was built and tested since no other device of the desired accuracy was connnercially available. Upon partial completion of the project, another Watt Transducer did become available which was essentially identical to our development. Since we could not economically compete with the manufacturer of these Watt Transducers, our project was stopped. Over a period of several months we thought about other ways to apply the experience gained from the Watt Transducer project, and came upon the idea of designing a precision multifunction power meter to help simplify the calibration of Watt and VAR transducers in the Instrumentation and Standards Laboratory, and possibly replace approximately five less accurate analog meters presently used by our Meter-Relay Craftsmen in their field testing. Since no similar meter was available, and since possible revenues lost to inaccurate measurement could justify the development costs of such a meter, we were given authorization to design and build it. This instrument is the Digital Multifunction Power Measuring System which measures the following electrical parameters to approximately plus or minus one-tenth of one percent or better accuracy: True RMS AC Volts in two ranges; True RMS AC Amps in six ranges; Watts in twelve ranges; VARs in twelve ranges; Phase Angle between Volts and Amps in all ranges; DC Volts in three ranges. This instrument has been completed, tested, and calibrated to its design accuracies and is presently being demonstrated within the BPA system to make its availability known to those personnel who might have need for such an instrument