To answer your question:
- You can send me a couple and I’ll test them.
- You can measure the shift with your IoTaWatt vs. your VT.
For option 2:
Install the CT on a conductor that will carry at least several amps. Loop the conductor through multiple times to multiply it if necessary.
Apply a purely resistive load. Incandescent light bulbs are good. Toasters are good.
Use the browser command: http://iotawatt.local/command?vtphase=INPUT where INPUT is the input channel of your CT.
If you get a large number, reverse the CT or the VT and do it again. I would guess that a CT like that will be less than 1. Add the result algebraically to the configured VT shift to get a reasonable shift value for the CT.
Shift varies with current, so there is no perfect answer, but with solid core CTs it’s usually low and behaves well at the low end. Nevertheless, try to do it at the typical current the CT will be asked to measure.
Couple of other things:
Those CTs don’t appear to have TVS diodes, so be careful not to energize the primary without shorting or connecting to the IoTaWatt.