ZMPT101B Zero Crossing Accuracy

By using ZMP101B, we can plot the AC voltage waveform real-time. I would like to ask if I can use it as my reference for zero crossing for synchronizing an inverter for grid tie set-up.

I would also like to identify not only zero crossing but also if it is going to positive peak or negative peak.

Yes you can.
Do you have just the transformer itself or the whole board?

This is how to use the board.
https://www.electroschematics.com/voltage-sensor/

You first need to establish the voltage you will get at the zero point. Probably the best way is to measure the voltage at both positive and negative peaks and divide by two.

Then subtract that from the voltage you measure. If the result is a positive number then you are on the top part of the cycle. If a negative one you are in the bottom part of the cycle.

When the numbers go from positive to a negative that is your falling zero crossing. When the other way round you are at a rising edge.

I will only use the board. Is it possible that there is a delay between the ac main and the serial plot of the arduino?

Not sure what you mean here?

It is possible that the transformer will cause a phase shift between the mains and the signal you get. If this occurs then it will be a fixed offset and simply to compensated for by a fixed time delay on the zero crossing timing in the software.

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Try reversing a set of transformer leads either the primary or secondary but not both. If it is in the US and many other places are they both on the same phase.

Will your building official and utility company accept a DIY device?

Where I live, an electrical "building permit" would be required for this application, and I very much doubt the inspector would sign off on a DIY device.

And my utility company inspector's brain would probably explode, too.

My house is already built so there no need for the permit and I will not apply for net metering. :wink:

Some things to consider: Not necessarily right now, but think of the future.

If you ever sell you house, a required inspection will turn up your project and checking will show no electrical permits or inspections. If you EVER need to have an electrician do something in your house, expect them to walk away because his work will require a permit and inspection.

Also, do you have a mortgage on your property? For several years my brother was an inspector for various mortgage holding companies. He found many things done like you are doing and the owner then had a choice of getting a new mortgage, removing and repairing all the work the owner had done, or hiring a licensed contractor to make it right.

Do you have insurance on your home? Insurance claims will likely bring an inspection and checking of permits. The insurance company also has your permission to inspect your property at any time.

What you seem to be planning to do[*] would be illegal where I live.

[*] it is not entirely clear, but it seems you plan to feed excess capacity back to the grid with a non-UL-listed device, without a "building permit" (req'd for electrical work on houses already built), and without utility company knowledge or approval.

If your intent is to transfer solar-battery inverter excessive output to the AC grid -- STOP NOW --
Power utilities have approved hardware that must be utilized. Installation almost always requires a specialty licensed electrician.

Around here, these units are popular (enough that many TV commercials are being sponsored.)
Powerwall 2 AC Utility Interconnection Support (azmag.gov)

I guess your suggestions is correct. In here, only once permit is process before construction and utility company will only inspect once. I am also aware of islanding. I guess I will use it on educational purposes.

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