Digital Power Meters Employ 16-Bit A-to-Ds

Yokogawa’s latest family of digital power meters, the WT300 series, can perform stand-by-power measurements, Energy Star and IEC62301 testing, and battery charger and other low level power measurements. The family consists of three models: WT310, WT310HC, WT330. The WT310 is a single-phase unit that can measure currents from 50 µA up to 20 A RMS. The WT310HC is a single-phase, high-current model with a current range from 1 A to 40 A RMS. The WT330 is available as a two- or three-element unit for applications on split phase and three-phase circuits. This model has a current range of 0.5 A to 20 A RMS. All models have voltage ranges from 15 V to 600 V RMS. To accurately measure certain waveforms, the WT300 uses high-resolution 16-bit A-to-D converters with a digitizing rate of 100 kS/s, and a bandwidth from DC and 0.5 Hz to 100 kHz, (20 kHz on WT110HC). Basic power measurement accuracy is 0.1% of reading plus 0.1% of range. Measured data is displayed on four 7-segment LED displays. The basic price for the single-phase WT310 is $2210; the three-phase WT330 starts at $3875.