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phil-kaddy avatar image
phil-kaddy asked

Can Current Transformer replace Energy meter

Hi Victron Community,

I am currently setting up a grid parallel ESS with a Multiplus 2, a Venus GX and two 5KWh Tesla Modules. I already have the Current Transformer/sensor (https://www.victronenergy.com/accessories/current-transformer-for-multiplus-ii ) for the Multiplus but no Energy Meter ET112.

Is my understanding correct, that

1. AC-In on the multiplus is bi-directional and can import to charge the batteries and export to power loads (I do not have any loads connected to AC-Out 1 or 2.)

2. I do not need to install the Energy Meter if I have the current transformer connected to the grid connection? (see picture below)

What changes to I have to make in my VE Config and ESS controls on the Venus to tell the Multiplus/Venus that the Current sensor is supposed to measure the import/export at the grid connection? I cannot see any options here apart from the tick-box in VE Config.

Any help would be much appreciated.


Any help would be greatly appreciated. Thank you, Phil

Schematics of my setup are below (except for the "No break loads, which I do not have):



battery chargingESSEnergy Metersensor
philby-ess-setup.jpg (17.2 KiB)
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4 Answers
nigelfxs avatar image
nigelfxs answered ·

Hi Phil

Answers to your questions:

1. Correct - "AC-In" is bi-directional.

2. Correct, but keep in mind that the current sensor cable is only 1m long. This means that the Multiplus 2 must be mounted close to the incoming mains cable.

I am also using the current sensor with the multiplus 2 and no other config changes are needed. I am not sure what the tick-box in VE Config does - my system appears to work the same whether it is checked or not!

Edit: When you plug in the external AC Sensor, it replaces the built-in sensor on AC-In. The Multiplus 2 can then adjust its power output so that the total grid power matches the configurable "Grid Setpoint" (see ESS settings).

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sean avatar image sean commented ·

As long as a sensible method is used, there is no reason why the supplied CT cannot be connected to the MP via an extended length cable - I have a number of installations using extended cables in excess of 30m long.

https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/extending-ct-cable

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ sean commented ·

Hi, great that it works well for you. Be aware though: we tested it extensively, hoping to be able to specify a longer max length. And decided against it after seeing the noise the system then picks up; as well as (un called for) variations in injection into- and power draw from- the grid.

its unfortunate; but that circuit isnt ideal.

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phil-kaddy avatar image
phil-kaddy answered ·

Thanks Guys. Much appreciated.

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Marcus Fosker avatar image
Marcus Fosker answered ·

Hi,

I have the same setup as you've shown with a MultiPlus 2 and I'm using the CT sensor. All works well most of the time.

I'm having some issues at higher currents as I've reached an upper limit and it would be good to compare notes and experiences if you wouldn't mind. How much current in total are you expecting to consume from the grid and what have you set AC Current limit to, either in VE Configure or in you GX?

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phil-kaddy avatar image phil-kaddy commented ·

Hi Marcus,

Overall we run a pretty low-key usage. Prior to installing a 6.5KW solar system in August this year (I live in Melbourne, Australia) I used about 13KwH a day on average (last two years). This is for a household of 3 Adults and 2 Kids. Since another family addition we have gotten a clothes dryer and now also heat the house with a reverse cycle air-conditioner instead of gas. I am still waiting on some longterm data but early indications are a new average usage of 20KwH a Day. So worst case (cloudy winter day) I am expecting to draw about 15KW from the Grid on an average, with solar providing the rest. Still not a lot, but we do not need to heat much in Australia and I don't have any pool pumps large fridges or the like installed.

I have just succeeded in setting up the Multi- and it appears to be working fine with the CT so far. It's nicely adjusting the battery charge so that we trickle export between 10-50W most of the time. My grid set point at the moment is at 50W in the GX and 35Amps limit in VE-Config.

I'm not sure if this helps but my understanding is that the 3000 Multiplus II can only charge with a max of about 1.5KW (30Amps @48V) and invert a max of 3KW from the batteries.


I hope this helps,

Cheers, Phil

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lackland avatar image
lackland answered ·

Updating 2+ years later ... Since mid-2021, Victron also sell a current transformer for the Multiplus-II with a longer 5m cable length (CTR110000550).

This is good to have when retrofitting storage to a house. No need to alter existing high-current AC wiring to fit an energy meter.

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ejrossouw avatar image ejrossouw commented ·

... and even a 20m version.

Current Transformer 100A:50mA for MultiPlus-II (20m)

CTR110002050

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