Using more CT in a PZEM-004T V3.0

Hello everyone,

I have a question regarding the usage of a PZEM-004T V3.0. I might start working with one of them but I would like to add more CTs to the device besides the one included when it is bought (check the link at the end). I know the CT is PZCT-02 (100A) from Peacefair.

So, to conclude, if I want to add e.g. 5 more CTs to have a total of 6 coils, would you suggest it? Have you done it? Did it work or would it work?

Thank you

Welcome to the forum Lorenzo.

I’ve never seen a PZEM-004T but I think what you’re proposing should work. It looks like your burden resistor is on your PCB and your CTs output a current. If you wire two CTs in parallel to that input, you should get the sum of the two circuits. You won’t of course be able to determine which circuit is responsible for the power being drawn - they’ll just all get added in together. A few things to note though:

  1. the circuits will all need to be on the same phase for that sum to be of any use
  2. that input is presumably designed for a max primary current of 100A so you’ll need to make sure the total current of all your circuits don’t exceed that
  3. be aware that those CTs hang off the Neutral line of the grid, which from a safety point of view is like hanging off the Active line of the grid - and in fact will be if you connect your L/N pair around the wrong way. So if you’re doing any CT cable extensions etc. you need to make sure any cable you use is up to the job with regards insulation specs etc. Isolate the mains connection before making any adjustments to the CT wiring.

Another note: all the c.t’s you parallel must have the same ratio, but not necessarily the same current rating.

Alternatively of course, can you route all the wires through the single c.t? Or some, to reduce the number of c.t’s?
2 wires through one c.t is the same as 1 wire through each, and paralleling the c.t’s.

1 Like