The transformer is Delta => wye
The service is 120/208V
277/480v initial voltage
Thank for your helps
This is still confusing to me possibly due to the way it's worded.
Above indicates the
service is 120/208v (Which usually indicates the
input voltage to the transformer)
Yet, above also indicates the "
initial voltage" is 277/480v with the transformer being a Delta primary with a Wye Secondary.
Regardless,
If the transformer is a
Delta primary with a 3ph Wye Secondary, Just because the "Service" Voltage or "Initial" Voltage is a "Wye Configuration with a Neutral", that does not mean a "Neutral" or grounded conductor is brought to the transformer's "line side" or "Delta" input,
nor should it be.
The neutral would only be brought to the primary if the transformer is a Wye input /Wye output type configuration.
Unless I'm wrong, (and I am often), it seems you have a standard 480v Delta Primary to 120/208v Wye secondary transformer.
In that case the primary feed to the transformer will only contain 3 phase conductors along with an equipment grounding conductor of some sort to bond the transformer's casing for fault clearing purposes.
The transformer produces it's own neutral on the secondary side or XO , which is required to be bonded.
Hence the interconnection of the grounded conductors on the primary and secondary side of the transformer, (Even though a Neutral is produced in the transformer) because they generally share a common grounding or bonding system.
JAP>
