Substation transformer 2

[encon5]

We will be installing a 2 MVA 23KV/480V delta-wye 3 phase oil-filled indoor substation transformer. The catalog shows the six terminals on the HV side. They call it loop fed. Can somebody elaborate on this.

Thanks.

encon5

 

[alehman]

It is probably designed for a loop circuit, i.e. continuation of the primary circuit to another transformer. Three terminals are the incoming circuit, three are for outgoing to the next.

 

[rcw retired EE]

Look carefully at the diagram. It may show two inputs to a disconnect switch or a removable fuse integral to the transformer. Six bushings would allow two three-phase ciruits to come into the transformer. In effect, the transformer is a convenient place to make a "T" tap on the line.

Imagine a group of these transformers wired in series with both ends fed from utility feeders. Any section of cable or any transformer can be taken out of service without a power outage on the other sections.

 

[peebee]

If it's loop fed, then alehman is dead on.

The other choice is called "radial" fed. Only one set of lugs. rcwilson is describing two radial-feed connections with a selector switch.