I have just started to build the prototype board shown in the picture. It occured to me the 3 CT’s might interact with each other. Each CT will monitor the current supplied to groups of 240 Vac LED light to detect whether it is on or not. All three groups of lights will be off the same single phase supply. Is it a bad idea to have the CT’s so close? I it is what would be a sensible seperation distance for the CT’s? I want to monitor each group seperately. Board is only temporarily laid out to sort component positions.
If all you’re interested in, is knowing whether you have a current above or below a threshold, I don’t think you need to worry. I’ve never tested a ring-core c.t. for this, I think I tested two split-core, and the cross-talk was detectable when the two were almost touching, but with some sort of space between, not significant; but I can’t remember the details.
For what it’s worth, an adjacent touching current-carrying conductor influences the c.t. by less than 0.2%.(a YHDC SCT-013-000).
Robert, thank you for the prompt reply. I’ll build the circuit and if there are any issues I’ll share my findings on the forum. I am, as you note, just using the CT’s as a check that the nominal expecteced current is flowing. If, the expected current is not flowing then there is a fault in the system. I have been very pleased with the accuracy of these 5A / 5Ma CT’s for current monitoring.
Many years ago now, I did a project with a large d.c. motor - 8 kA peak armature current, and that required quite a lot of copper, I think it was 8 wires of 630 mm² in parallel!
Robert, well spotted, amazing what a bit of capitalization can do! However, I think 5mA is more in my league.