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raymiller avatar image
raymiller asked

Current Transformer for MulitPlus II - can the cable be extended and what is the maximum cable run?

If I implement the Current Transformer (CT) recommended for the MulitPlus 2 and install it at the Grid interface point. What is the maximum cable distance?

I looked up the specification for the Current Transformer YHDC.com SCT013 100A:50ma shows this CT model is terminated at the measuring interface in a 10-ohm resistor to achieve a 1% accuracy. Another poster measured the MulitPlus 2 input resistance at 40ohms, I'm yet to confirm this.

With such a low impedance required for the CT would indicate the wiring Extention could be very limiting or the cable size (mm2) would need to be increased.

What is the recommended loop resistance of the CT wiring to keep the calibration of the CT in the Victron implementation?

Can the CT be calibrated in software?

Or has anyone else successfully increased the CT wiring over any distance?

Thanks in advance for any info.

ct
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raymiller avatar image raymiller commented ·
I've just measured the "Burden" resistance (or the termination impedance within the MuitiPlus) of the Current Transformer in MulitPlus 2 at 60 ohms.

I am assuming then that Victron Engineering has programmed the MulitPlus to calibrate the recommended CT SCT013 100A:50ma with the changed "burden" 60-ohm resistor (from the 10-ohm shown in manufactures specification of the product).








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2 Answers
Alexandra avatar image
Alexandra answered ·

@RayMiller

Because the signal is not huge from the CTs you may find extensions can cause issues.

There will be noise, inaccuracies and other issues like unintended feedback. I have seen it discussed in various threads on the forums from trying to extend. The consensus on one thread was to use an energy meter for accuracy especially over a distance.

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roblatour avatar image
roblatour answered ·

I know this is an old thread, but these that may be of interest to anyone looking into this post ...

Victron CTR110000550 - Current Transformer 100A:50mA for MultiPlus-II with a 5 meter (~16.4 foot) cable,

and

Victron CTR110002050 - Current Transformer 100A:50mA for MultiPlus-II with a 20 meter (~65.6 foot) cable.





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