230/115 kV power transformer neutral terminations
230/115 kV power transformer neutral terminations
(OP)
a 230/115 kV power transformer has two neutral points brought out through oil/oil bushing similar to phase connections.
The cable compartment interface is similar to phase ones though the neutral points will be solidly earthed and no HV is supposed to appear on these points.
To save some money, Utility proposes to use "dummy" terminations just for oil sealing, or to ask the transformer manufacturer to modify the compartment base plate to contain a LV cable connection (oil-sealing gland?) enabling to terminate a 240 sq.mm cu LV grounding cable.
I have not been dealing with this type of connections before, any clue?
The cable compartment interface is similar to phase ones though the neutral points will be solidly earthed and no HV is supposed to appear on these points.
To save some money, Utility proposes to use "dummy" terminations just for oil sealing, or to ask the transformer manufacturer to modify the compartment base plate to contain a LV cable connection (oil-sealing gland?) enabling to terminate a 240 sq.mm cu LV grounding cable.
I have not been dealing with this type of connections before, any clue?






RE: 230/115 kV power transformer neutral terminations
As a consequence we use standard MV (oil to air) bushings for neutral, and connect a couple of LV cables from neutral bushing terminal to the ground (see attached imagage).
Si duri puer ingeni videtur,
preconem facias vel architectum.
RE: 230/115 kV power transformer neutral terminations
I am asking about the connection of oil compartment cable into neutral with a LV cable instead of HV cable.(though the neutral is solidly earthed)
Sketch attached.
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
115 kV ungrounded wye? Never saw that.
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
RE: 230/115 kV power transformer neutral terminations
the most effective solution is to ask to the transformer manufacturer to modify the neutral bushing, installing a MV oil-to-air bushing. Which kind of neutral bushing was required in the spec?
By the way 110 (or 115) kV sub-transmission networks in central Europe (typically Austria) often used resonant neutral grounding, so that the neutral is always fully insulated.
Si duri puer ingeni videtur,
preconem facias vel architectum.
RE: 230/115 kV power transformer neutral terminations