How I calibrate ACS712 30A current Senor ZMPT101B voltage sensor Calibration Values for emonlib
I didn’t read these but there are a few articles on the ACS712 current sensor in the old OEM forum. Maybe one of these may help:
https://www.google.com/search?q=site:openenergymonitor.org/forum-archive+ACS712
EDIT: Update link to old forum
The general calibration principles, and the derivation of the constants, is in the ‘Learn’ section under Electricity Monitoring > Current & Voltage.
The ZMPT101B appears to be a current transformer intended for very low currents. The operating principle appears to be that a multiplier resistor turns the mains voltage into a primary current, and the secondary current develops a voltage proportional to the mains voltage across a burden resistor. The claims are that this is more accurate than a standard isolating transformer as contained in our a.c. adapter. With a knowledge of the multiplier and burden resistor values, you should be able to design the appropriate interface (you may need to change the values from those used with the Ideal a.c. adapter) and calculate the calibration constant.