EVALSTPM-3PHISO

EVALSTPM-3PHISO evaluation board implements a complete three-phase energy meter with low-cost shunt current sensors. The solution is based on the STPMS2 device, a double channel, 24-bits second order sigma-delta modulator, measuring voltage and current for each phase through a voltage divider and a shunt current sensor. Sensing circuitry and PCB layout are optimized to maximize signal-to-noise ratio for optimal accuracy. The STPMS2 oversamples the signal using a 4MHz clock distributed in a synchronized way by the microcontroller and outputs voltage and current sigma-delta bitstreams, multiplexed on the same pin. The two-wire communication between STPMS2 modulator and MCU is isolated by STISO621W, 6KV galvanic isolated interface, allowing up to 100 Mbps rate and low pulse distortion (3ns) for safe and fast data transfer between isolated domains.

• Compliant to EN 50470-x, IEC 62053-2x, ANSI12.2x standard requirements for AC watt meters
• Accuracy Class 0.5 according to IEC 62053-22 on 3-ph active/apparent power measurement
• Accuracy Class 1 according to IEC 62053-21 on 3-ph reactive power measurement
• 6 channels voltage and current decimated samples available at 200us
• 5KHz measurement bandwidth
• RMS and THD (optional) calculation of each voltage and current signal
• Selectable high pass filter for DC measurement
• Line period and phase shift measurement for each phase
• Phase voltage delays
• Full calibration (amplitude, power offset and samples offset for DC measurement)