polarity of ground fualt detection ct on the neutral
polarity of ground fualt detection ct on the neutral
(OP)
is there a season why the polarity of a GF detection CT on the neutral is setup as if the flow of current is from ground , through the NGR to the neutral point?






RE: polarity of ground fualt detection ct on the neutral
But this is ac current, so actual direction of current flow is not the issue.
David Castor
www.cvoes.com
RE: polarity of ground fualt detection ct on the neutral
As far as CT polarity, it should be away from the device.
RE: polarity of ground fualt detection ct on the neutral
RE: polarity of ground fualt detection ct on the neutral
CTs should be connected so that the wye point of the CTs points toward the protected zone and other side gets connected to the polarity terminal of the relay. Same goes for a neutral CT, it should be grounded on the equipment side and connected to the polarity of the relay on the side away from the equipment. It's nice when it happens that the polarity of the CT connects to polarity of the relay, but means nothing really. For the relay connections, forget that the CTs even have polarity marks, just go with the correct wiring relationships. For your testing, current from ground to the X0 terminal should be in phase with current from the CT into the relay.
RE: polarity of ground fualt detection ct on the neutral
The single line or wiring scematic can then be followed
where REF or DIFF cts require the correct polarity in relation to each other.
For SBEF polarity is not important.
RE: polarity of ground fualt detection ct on the neutral
the polarity of the CT is marked so as for the first half cycle the current flows from the ground to the neutral point. this CT is a zero sequence current transformer with only the neutral conductor going through it.
My question is why would charge flow from ground potential to the neutral potential? in what case is the neutral at lower potential than ground?
RE: polarity of ground fualt detection ct on the neutral
RE: polarity of ground fualt detection ct on the neutral
------------------------
It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant
RE: polarity of ground fualt detection ct on the neutral
As to how the current could flow from the ground to the neutral, consider a single phase ground fault. If current flows out of the phase bushing, it flows through the ground and from the ground into the neutral bushing. The ground potential is a consequence of the current flow, not the cause. The driving force of the current is the transformer winding voltage.
RE: polarity of ground fualt detection ct on the neutral