OT. Current transformer and 3.3kv motor cable

This is off topic I know, but I would appreciate some guidance. I have a 3.3kv motor, the current of which I need to make available to a PLC (4-20mA). I have used some LEM c.t.'s before with integral 4-20mA outputs but only on low voltage 415 volt circuits. If my 3.3 kv motor cable leg is well insulated would there be a problem with using one of these LEM c.t's? The current is around 30 amps.
I should point out that any installation would be done by high voltage trained personnel. Just mnot sure about the voltage.

Should not matter if the cable is a fully insulated cable. Would you wrap your hand around /touch the cable while it is energized? If so, your CT should not care about voltage...

BTW, is it a shielded cable?? If so the CT will not work, as the current will cancel to 0 if you are using the shield as part of your neutral...

If the cable has all three phases in it merely passing the whole cable thru a CT will NOT work. The 3 phases will cancel to zero. You will need to read the current using CT on one or more phases which means you will have to open the cable to separate the phases.

Dan Bentler

Good point Dan, being in the US when you mention cable we think of individual conductors (wire), especially for 4kv level insulations. I believe that EU uses mostly cables with multiple conductors

When I think cable in electrical work I think of multi conductor.

Dan Bentler

leitmotif said:

When I think cable in electrical work I think of multi conductor.

Dan Bentler

Click to expand...

Agreed Dan, cable = multi, core = single this side of the pond

Cable= 1 single core

By cable I meant 1 core of the 3 phase supply

We've used other amp transmitters on 4160 VAC without problem on insulated conductors (one conductor per transmitter, as pointed out above). Remember - the insulation is supposed to prevent a path to ground even if it lays against a bare metal conductor like a conduit. It isn't going to short out through a transmitter that is itself insulated.