5kV cable
5kV cable
(OP)
I'm working on the 5kV standby generation at the water treatment plant. I spec'd out that each 2000kW gen must have 500MCM cable connected to the 4160V bus. My question is, does the cable needs 1/3 concnetric neutral, if not, how are we going to ground this, or does it need the ground at all?
Thank
jimmy
Thank
jimmy






RE: 5kV cable
Concentric neutral cables are used by utilities for UG distribution systems to avoid the need for a second conductor. They are not often used for industrial/commerical power systems.
RE: 5kV cable
The “one-third neutral” cable is a typical rating for underground residential distribution in electric utilities. For industrial applications, it is more common to use tape-shielded cable, or for 4160V, unshielded cable.
In all cases, do not rely solely on the cables’ concentric neutral or tape shield for equipment grounding/bonding of the generator-set enclosure . System grounding {of the genset stator winding} is a completely different issue.
RE: 5kV cable
You will need to do a fault current calculation and look at both 3phase and phase-to-neutral fault levels. Depending on the generator's zero sequence impedance, you may need to install current limiting resistors or reactors in the neutral circuits. Consult carefully with your generator manufacturer.
I agree with the above comments regarding concentric neutral cable. You also need to ensure that your overcurrent protection is adequate to prevent damage to the grounding conductor whether it is cable shield and/or a separate wire.
RE: 5kV cable
RE: 5kV cable
RE: 5kV cable
I don't believe NEC would require any ground wire be run with the phase conductors [please verify we're all talking US codes here]. I believe this statement is true regardless of system grounding (solid/resistance/reactance/ungrounded). I could be wrong and would certainly invite comment on this.
RE: 5kV cable