HV Neutral Conductor
HV Neutral Conductor
(OP)
I have a question about the voltage rating of neutral conductor for solidly grounded 230kV shunt reactor. NEC 250.184(A)(1) states that for solidly grounded systems greater than 1kV, the insulation of neutral conductor has to be minimum 600V.
So for 230kV solidly grounded shunt reactor, the insulation of the neutral conductor (from star point to ground) has to be only 600V. Is it correct? Thanks.
So for 230kV solidly grounded shunt reactor, the insulation of the neutral conductor (from star point to ground) has to be only 600V. Is it correct? Thanks.
RE: HV Neutral Conductor
Most reactors that maybe air core, would have a fence around them for safety.
Reactors that are under oil, would be treated like a transformer.
Hope that helps.
RE: HV Neutral Conductor
RE: HV Neutral Conductor
I’ll see your silver lining and raise you two black clouds. - Protection Operations
RE: HV Neutral Conductor
It is not clear but it looks that in IEC world: for solidly grounded systems greater than 72.5kV, the insulation level (Um) of neutral cable has to be minimum 17.5kV. What do you guys think about it?
RE: HV Neutral Conductor
RE: HV Neutral Conductor
RE: HV Neutral Conductor
"....I have a question about the voltage rating of neutral conductor for solidly grounded 230kV shunt reactor. ..... So for 230kV solidly grounded shunt reactor, the insulation of the neutral conductor (from star point to ground) has to be only 600V. Is it correct? "
1. I take it that the length of the conductor in question is :
(a) from the shunt reactor to the ground. This conductor is NOT Neutral conductor. It is a grounding conductor; maintained at ground potential.
(b) from the transformer start-point (Neutral) to the shunt reactor. which is NOT maintained at ground potential.
2. For above 1 (a), the grounding conductor can be bare. It is intended to be connected to the grounding electrode, which is always bare. If insulation is applied for other than electrical safety reasons, 600V would be acceptable.
Che Kuan Yau (Singapore)
RE: HV Neutral Conductor
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RE: HV Neutral Conductor
I think electrical safety would not be an issue here because it is a grounding conductor which connects the star point of shunt reactor to the ground. However insulation might still be required to avoid corrosion and to insulate this grounding conductor from other metal parts like cable trays; and for that 600V insulation should be sufficient.
RE: HV Neutral Conductor
Mr. timm33333 : "....So for 230kV solidly grounded shunt reactor, the insulation of the neutral conductor (from star point to ground) has to be only 600V. Is it correct? "
I take it that it is NOT a Neutral conductor. It is a Grounding conductor, connecting to the ground electrode. NOT distributed as Neutral.
With this clarified., pleased advise your learned opinion.
Che Kuan Yau (Singapore)
RE: HV Neutral Conductor
EHV shunt reactors are used in two modes- bus reactors in substations and line reactors for compensating the capacitive MVAR of transmission lines. In the former case neutral is solidly grounded and a 38 kV insulation level is sufficient. But the neutral of the line reactors is usually grounded through a small inductor(neutral grounding reactors) for single pole reclosing. The Neutral reactor will compensate for the capacitive current during LG faults. ( to reduce arcing)
In the case of EHV line reactors (400-800kV), the neutral insulation level is 145 kV class (550 kV BIL) to take care of the neutral over-voltages during LG faults. In India, for interchangeability, we provide 550 BIL for the neutral of all EHV shunt reactors.
RE: HV Neutral Conductor
RE: HV Neutral Conductor
RE: HV Neutral Conductor
@ prc (Electrical)16 Jan 23 16:25
Thank you for your learned advice. Please take note that Mr. timm33333 stresses:
"...As mentioned above, we are talking about the insulation of grounding electrode conductor which connects the star point of shunt reactor to ground. We are not talking about the insulation of neutral terminal of shunt reactor."
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Che Kuan Yau (Singapore)
RE: HV Neutral Conductor
For cases where the neutral is intended to be grounded, it is our custom to use a 15kV bushing, that is common with what we stock for spares.
I say 15kV because most of what I do is in substations. Distribution transformers are so common that if we stock spares (I don't know, but I expect so), there are likely several types.
Also transformer core grounds are also on 15kV bushings.
RE: HV Neutral Conductor
RE: HV Neutral Conductor