TurbineGen
Electrical
- Mar 1, 2007
- 489
I have a question regarding a mobile substation we have. The sub is a 230kV, 25 MVA 2 part mobile unit. The transformer is an odd design with the high voltage bushings mounted at the base of the transformer rather than the top and they come out at an angle to achieve clearance. There are arrestors on swing pivot arms that fold out once the trailer is in place. Cables are run from the transformer HV bushings, over the arrestors to the switch trailer and then to the line where they hook up.
The manufacturer is using 4/0 bare copper cable with a heat shrink covering made to fit the sub to run from the transformer to the arrestors and then to the switch trailer. Clearance at the HV bushings is approximately 1.5 meters phase to phase and 2 meters phase to phase at the arrestors/switch trailer. I have never heard of 230KV being wrapped in heat shrink with distances so close. Why is this heat shrink necessary necessary? Are they using it as insulation? Weather protection? There is no shield or anything so wouldn't the heatshrink just be destroyed by partial discharge/corona after only a few years? Should we be equipping the unit with a shielded cable or is this set up ok?
Please let me know your thoughts.
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
The manufacturer is using 4/0 bare copper cable with a heat shrink covering made to fit the sub to run from the transformer to the arrestors and then to the switch trailer. Clearance at the HV bushings is approximately 1.5 meters phase to phase and 2 meters phase to phase at the arrestors/switch trailer. I have never heard of 230KV being wrapped in heat shrink with distances so close. Why is this heat shrink necessary necessary? Are they using it as insulation? Weather protection? There is no shield or anything so wouldn't the heatshrink just be destroyed by partial discharge/corona after only a few years? Should we be equipping the unit with a shielded cable or is this set up ok?
Please let me know your thoughts.
------------------------------------------------------------------------
If it is broken, fix it. If it isn't broken, I'll soon fix that.
