TIZIANO BIELLI

Pk-RMS WATTMETER:

PK-RMS is a low price high speed programmable wattmeter capable of measuring voltages, currents, powers and frequencies 50 times per second. Readings can be saved to microSD in real time (csv format).

PkRMS strum front PkRMS strum internal

This first prototype is based on an "Arduino Nano Every" development board (ATmega4809).
The MCU's internal 10bit ADC samples the attenuated voltage, coming from the voltage divider, the current, coming from the CT and the 0.6V reference voltage.
The ADC uses the internal 1.1V reference and since it can't measure negative voltages the AC inputs needs to be offset by the 0.6V reference (close to half of 1.1V).

PkRMS strum internal PkRMS schematic
PkRMS simplified schematic

The meter synchronize to the AC input by counting the zero crosses. Before outputting a reading, depending on the selected speed, it will wait (and sample) for a certain number of zero crosses. If DC is applied, no zero voltage cross is detected, and after a certain time limit, the meter will output a reading and start a new sampling cycle.

PkRMS HighVoltageFlashoverRecordjpg

Recorded Data Example

Published: 2023-04-01, Last edit: 2023-10-13

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