Hi all!
There is a project, where a subcontractor will be doing the substation local, and all its related electrical stuff from the MV side..
I have been discusing with him the low voltage side, specially the grounding of the neutral.
The transformer will be a dry 1000KVA, 15/0,4KV delta/wye.
The transformer will be 80meters away from the facility and distribution board.
First question.
Should we carry the PE cable from the substation till the facility ? im asking this from a practical point of view. I know this has to be done if the distribution system we use is TN-S and the neutral is grounded in the substation. but should we use TN-S this way? is it worth ?
Could we only carry the neutral and ground it just before the facility ?
We could also use TT system and then we would have 2 independent grounds, one in the substation for the neutral and another one in the facility.. in this case i MUST use residual circuit breakers,
The reason why i would like to use TN-S system is because the phase-ground faults would have a much higher current and if designed correctly the magnetic of the circuit breakers would trip in each branch circuit.
This will be a facility with a lot of motors.
Anyway if using one or the other distribution system I will put a toroid with a ground fault relay, regulated high enough so it doesnt trip incorrectly.. in the main circuit breaker of the facility.
Attached pictures of schemas,
Open to opinions, thanks!
There is a project, where a subcontractor will be doing the substation local, and all its related electrical stuff from the MV side..
I have been discusing with him the low voltage side, specially the grounding of the neutral.
The transformer will be a dry 1000KVA, 15/0,4KV delta/wye.
The transformer will be 80meters away from the facility and distribution board.
First question.
Should we carry the PE cable from the substation till the facility ? im asking this from a practical point of view. I know this has to be done if the distribution system we use is TN-S and the neutral is grounded in the substation. but should we use TN-S this way? is it worth ?
Could we only carry the neutral and ground it just before the facility ?
We could also use TT system and then we would have 2 independent grounds, one in the substation for the neutral and another one in the facility.. in this case i MUST use residual circuit breakers,
The reason why i would like to use TN-S system is because the phase-ground faults would have a much higher current and if designed correctly the magnetic of the circuit breakers would trip in each branch circuit.
This will be a facility with a lot of motors.
Anyway if using one or the other distribution system I will put a toroid with a ground fault relay, regulated high enough so it doesnt trip incorrectly.. in the main circuit breaker of the facility.
Attached pictures of schemas,
Open to opinions, thanks!