Earthing on the neutral
Earthing on the neutral
(OP)
What is an isolated neutral system?
Is this the same as an unearthed system ?
How does it differ from direct earthing and impedance earthing?
Is this the same as an unearthed system ?
How does it differ from direct earthing and impedance earthing?






RE: Earthing on the neutral
Isolated ground is a more familiar term.
Rafiq Bulsara
http://www.srengineersct.com
RE: Earthing on the neutral
see pic attached.
I'have never seen this exept in book.
RE: Earthing on the neutral
ECT 172 probably answers your specific question about IT systems plus a load of related ones you haven't thought of yet, and the whole document set is available here.
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If we learn from our mistakes I'm getting a great education!
RE: Earthing on the neutral
As far as I can remember, IT (per IEC 60364) system of earthing is still being used in Norway for 400 V domestic network and the earth leakage protection was provided by overcurrent protection at the early stages.As there were lot of house fires due to this grounding method,subsequently Residual Current Circuit Breakers (RCCB)were introduced for earth leakage protection in domestic installations.
Anybody from Norwegien power system experience please correct me.
RE: Earthing on the neutral
"isolated neutral system" & "unearthed system" I guess you're talking about distribution networks with no link between neutral and ground.
Usually you can operate with neutral isolated from the ground if the capacitive currents are lower than 10 Amps and with neutral "compensated" with Petersen coil or "treated" with resistance for capacitive currents higher than 10 Amps.
Like I told you in another thread, there's no earth fault (short-circuit)for single phase touching the ground in isolated neutral from ground operation. Due to low current magnitude and increase of voltage from phase-ground to phase-phase on the healthy remaining phases,you can decide to continue operation for a limited amount of time, that's the advantage. The disadvantage is that you may end up with broken isolation or affecting the long time health of the isolation.