EVALSTPM-3PHISO, Evaluation Board, STPMS2/STISO621W/ STM32F413RH, Energy Meter

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)