ZCT positioning 1

[electrolitic]

Situation: 4.16 kV AC motor (2000kW) starter using reactor (externally mounted). Panels for master CB and reactor short CB mounted side by side.The best position for ZCT would be just after the master CB , I suppose.
Question: How to do it in terms of mechanical arrangement?

 

[7anoter4]

Could you provide a schematic diagram?

 

[electrolitic]

I will try to "draw it":
Three main components: One master circuit breaker, one reactor short circuit breaker, one reactor(external).
Master circuit breaker from 4.16kV busbar.
After this master CB circuit is divided in two branches.
One goes to the starting reactor. The second goes to the incoming side of short circuit breaker.
The outcoming side of short circuit breaker is also divided in two branches.
One goes to the reactor and the other goes to the motor.
If ZCT is installed just after the master CB (before the point where circuit is divided in two) motor and reactor will be protected against ground fault by the panel protection relay.
How to do it in terms of mechanical arrangement?(cables, busbars?)
Thanks

 

[7anoter4]

ZCT [Zero Current Transformer] is connected with toroidal ground transformer. It has to be mounted in the enclosure of main CB and the electronic part of the ZCT will be fitted in the control part of the enclosure.
The toroidal transformer has to be mounted on the cable before terminating will be executed. If the cable is shielded the shield to grounding wire shall be return through the toroidal transformer before it will be connected to grounding.

 

[electrolitic]

Thanks 7anoter4
Surely the misunderstanding is caused by my bad english.
The motor starter using reactor needs a connection between main and short circuit breakers, normally using busbars.
The ZCT is normally designed to embrace insulated cables.
The use of cables to interconnect busbars inside panels is not allowed, I suppose.
Most of designers just apply one ZCT located at motor cabling.This means that the reactor(externally mounted) and its cabling will not be properly protected against ground fault. What I do is to aplly two ZCTs, (one at reactor incoming cabling and a second at motor cabling) adressed to two overcurrent relays that trips the main breaker.
I never found a relay with two inputs for ZCT.
My references are Schneider SEPAM/GE Multilin/MIF relays.
Am I doing the right thing?
This was the reason of the question.

Anyway, thanks again.

 

[7anoter4]

First of all I have to recognize your English is better then mine!
Second, you are right, the ZCT has to be mounted on all three cores of a cable supplying entire load. If the main CB is connected with incoming [utility or else] by cables- even if it could be outside of your property- I think ZCT could be mounted on this cable. But if the terminating of the supply cable is already made [by Utility, may be] it is still a problem.
An other solution is to prepare 2 system of ZCT: one for reactor and second for motor independently. It is more expensive, indeed. I don't think the solution to combine both in a single ZCT it is possible. At least you need two toroidal transformers, one in each location. You have to ask the ZCT manufacturer if the electronics may be common.