Transformer connection
Transformer connection
(OP)
We have a utility supply of 24.9/14.4 kv.
The project is a new water treatment plant and the MCC would be 600v.
What is the best selection for primary and secondary connections?(delta-wye-...)
What are the parameters to be considered?
Any reference would be appreciated.
Regards,
Surineman
The project is a new water treatment plant and the MCC would be 600v.
What is the best selection for primary and secondary connections?(delta-wye-...)
What are the parameters to be considered?
Any reference would be appreciated.
Regards,
Surineman






RE: Transformer connection
Check h
RE: Transformer connection
Ungrounded 3-wire 3-phase is banned by law in New York State unless it is a separately derived system that is confined to a single building.
You still need both service and feeder ground fault protection for either system that is automatic. For branch circuit ground faults a current transformer and cheap ammeter with manual tracing will work on a resistor grounded system that has say a 1 hour ground fault delay at the service and 1/2 hour at the feeders. However, getting integrated ground fault protection that is that slow is hard to obtain.
A resistance grounded system is also less painful in a certain body part if you have a double ended switchboard, cogeneration, or both. Solidly grounded is less painful in that all ground faults will clear automatically.
RE: Transformer connection
RE: Transformer connection
There are about a dozen specific examples, and I believe they are in the Red Book.
RE: Transformer connection
Somewhat strangely, SquareD lists their type NF panelboards and circuit breakers in the Digest as rated 277/480 volts but the panelboard nameplate will usually read 480Y/277 volts.
It does not really matter what the order is, just as long as we the lower number is the phase to neutral voltage. The only possible confusion is that there is such as thing as 120/240 volts single phase 3-wire and 240/120 4-wire delta 3-phase. However, the latter system should always say, $-wre delta 3-phase" to avoid confusion especially if you have the bogus 240/480 4-wire delta 3-phase system where the high leg is 416 volts to neutral.