A Novel Method for the Measurement of Power, Power Factor, rms, and Average Values of Voltage and Current of Distorted Power Frequency Waves

A new method for processing of basic electric values

“…The realized instrument was checked in the laboratory, by using a measurement system that is described in detail in [13]. Figure 6 shows a block scheme of the system realized in this way, where the measuring of the alternating values is done by asynchronous sampling, using a new definition for calculating the average and effective value, suitable for application in measurement [14]. The process makes use of the capacities of the digital system voltmeter HP3458A-the synchronization of the measurement moment and fast measuring of dc voltage, with high precision.…”

“…rms value, the error that is introduced by the asynchronous sampling is significantly reduced. It has been shown that the errors introduced by this method can be corrected by an adequately favourable selection of the beginnings for the measurement interval and the number of samples [14]. The number of samples in each period is not fixed, because a pre-condition to define the beginning and the end of a period is to determine whether the measured value is smaller or bigger than its own previously calculated rms value.…”

High precision calibration of ac current-to-voltage converters

“…So, the agreement in power measurement shows indirectly the agreement in the ac resistance measurement. The author of this paper calibrated, using asynchronous sampling [8] and ac-current-to-ac-voltage conversion according to figure 1, one power converter MSB that was previously calibrated at PTB. The discrepancy at various power factors (one, zero inductive and zero capacitive), at 120 V, 4 A and 53 Hz, was found to be less than 4 ppm, much less than the uncertainty of the MSB instrument.…”