Description
The 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 4 MHz clock distributed in a synchronized way by the microcontroller and outputs voltage and current sigma-delta bitstreams, multiplexed on the same pin.
FEATUREs
• Compliant to EN 50470-x, IEC 62053-2x, ANSI12.2x standard requirements for AC watt meters
• Active wideband, active fundamental, reactive and apparent power/energy calculation for each phase and cumulative
• 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 @200 us
• 5 kHz 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)
• Two configurable LED for pulsed outputs
• Communication through USB in virtual com port mode with shell commands
• 6 kV galvanic isolation between the phases with 8 mm creepage and clearance