question

spudgun avatar image
spudgun asked

Parallel MultiPlus - Current Transformer

For an ESS system with Multiplus II units in parallel I wanted to use a CT Clamp instead of an ET112 meter to measure the grid. I saw a statement somewhere before, saying that this won't work, but I'm not sure why it won't work. Can anyone explain why an ET112 or similar is needed instead of a CT Clamp? Or can a CT be used, maybe I have the wrong information?

Multiplus-II
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3 Answers
Rob Duthie avatar image
Rob Duthie answered ·

The only thing i found out was it was more accurate in current measurments by using the ET112. The CT clamp was not very acurate in its readings and also the short lead was a issue reaching meter boards that were not in the same location etc.

The ET112 uses RS485 so longer range. There was one other thing but can't recall it, thats is why i used a ET112 meter.

Regards

Rob D

NZ

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ejrossouw avatar image
ejrossouw answered ·

The Victron CT clamps are now available in 1, 5 and 20m. It offers an easy install vs that of ET112. The CT replaces the MP's internal meter, which if you want to shows critical loads, will not be possible I discovered.

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pcbl avatar image
pcbl answered ·

I have a multiplus ii with a CT clamp sensor (5m) which works great and has a response time which is faster than the ET112,

Victron ESS + ET112 = slow response - Victron Community (victronenergy.com)

I then added a second multiplus to the system to work in parallel, keeping the CT clamp on the master unit, nothing on the slave unit. This works fine in keeping the grid at around 50W set point. However, cerbo GX (Gateway) will read the current incorrectly, thus falsely report a lot of power going in and out of the grid while the multiplus pair keeps it near 50W.

This post is also relevant.

Multiplus-II + ET112 + Current Transformer - Victron Community (victronenergy.com)


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