Cable Fill in a Ground / Zero Sequence CT?
Cable Fill in a Ground / Zero Sequence CT?
(OP)
If I have a window type ground/zero sequence CT, with a 7.5" window diameter, are there any standards for how much cable can be passed through this CT?
I have 12 conductors (4x3Cx___MCM) [can't remember gauge exactly], and the cables are a very tight fit. I'm worried about the pressure this causes on the CT, and potential overheating in that small area due to thermal dissipation from the cables.
Thoughts?
I have 12 conductors (4x3Cx___MCM) [can't remember gauge exactly], and the cables are a very tight fit. I'm worried about the pressure this causes on the CT, and potential overheating in that small area due to thermal dissipation from the cables.
Thoughts?






RE: Cable Fill in a Ground / Zero Sequence CT?
if you read the last paragraph on this technical doc. by Siemens:
http://www.energy.siemens.com/us/pool/us/power-dis...
CT opening, and should not be allowed to contact the CT
case. If the cables are directly against the CT case, it could
lead to localized saturation of the CT core under throughfault
conditions, leading to false operation. Typically, the
mounting plate for the zero-sequence ground CT can be
used to restrict the cables so that they pass through the
approximate center of the CT window.
RE: Cable Fill in a Ground / Zero Sequence CT?
Might be best to select a larger ID sensor, but please beware of the type of sensor you have, or will order. If it is just a simple 50:5 or 100:5 CT for example, then placement of cables can be critical. If the sensor is designed for zero-seq in true core balance scheme, then placement of conductors is not so important. There are not many CT suppliers who recognize this or offer different type winding for core-balance application.
Hope this helps....