Aggregate reading from multiple c.t's?

Hardware
1

Following on from my previous query Wiring of CTs for controlling a battery alongside a surplus diverter where I ended up doing some “c.t. arithmetic” by passing two cables through a single c.t. in order to get an aggregate measurement.

I’m now wanting to extend the “arithmetic” by “subtracting” another load from the resulting c.t. reading, but it’s not convenient to route the new cable through the one c.t. Two reasons - the cables are too bulky for a regular sized 100A:50mA c.t., and the resulting load rewiring would be untidy/less safe.

It occurs to me that it may be possible to replace the single c.t. with multiple c.t.s - perhaps one for each load cable and then parallel the c.t. tails at the input of the metering device (which in my case is a Victron Multiplus2 Inverter).

Is this a useful technique and if so what limitations should I take care with?

Many thanks, David.

2

If you are using genuine current-output c.t’s, then connecting them in parallel results in the currents adding (or of course subtracting if you reverse one of them - either with the direction of the primary (the cable) or with the secondary connections). If they are the voltage output type, then wiring in series will have the same effect. Both c.t’s must have the same sensitivity, or you’ll need to be inventive and you might need an additional burden for one of them, the aim being to make them appear to have the same sensitivity at seen at the input to your inverter.

3

Thanks Robert.
I’ll be using the c.t’s from the shop at Current O/P: 100A max clip-on current sensor CT - Shop | OpenEnergyMonitor
So I’ll connect them in parallel.
Really appreciate your fast reassurance.
David.