SPice10212 - 3-phase VAC measurement
The SPice10212 provides 3 channels of AC voltage measurement. It is primarily intended for monitoring up to 3 phases of the mains (line). Input voltage isolation and scaling is provided by external, user supplied transformers.
Typical applications include standby generator controls and phase failure monitoring in large HVAC or industrial compressor systems.
Safety warning: This board is intended for use with user supplied transformers to isolate the board from the voltages being measured. It is your responsibility to make sure you use appropriately safety rated transformers and wire them safely and correctly.
The board comprises three independent full wave rectifiers, smoothing filters and calibration potentiometers. It is intended that the transformers you supply will scale the input voltage to nominally 24VAC full scale. In other words, you would use transformers with a primary voltage equal to what you want to measure and 24VAC secondary windings which you connect into the SPice10212 board. The calibration potentiometers allow you to adjust out the effects of transformer regulation.
Note: This is not a precision measurement system. Accuracy depends on a number of factors, mainly how well you calibrate the system. Because it uses simple rectification, it will be inaccurate at low input voltages. Resolution is 1/1024 of the full scale range you aim for. This will be roughly 1V for 240VAC full scale and roughly 0.5V for 120VAC full scale. This is an average responding system, not a true RMS system. The frequency range is 50/60Hz. See also Nonlinearity correction.