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1.2 Applicability
When present, the input transformer is always a 208 V primary to 480 V secondary
autotransformer with a circuit breaker between the transformer and the UPS. If input is wye
configured, the input neutral connects to the autotransformer and the ground bond in the
UPS is removed. If input is delta configured, the input neutral terminal is not used.
An autotransformer with 208 V primary to 480 V/277 V secondary is used for the
following:
o
208 V wye to 208 V/120 V wye
o
208 V wye to 480 V/277 V wye
o
208 V delta to 208 V delta
o
208 V delta to 480 V delta
The output transformer always has a breaker between the UPS output and the transformer
primary. There are three configurations of three phase output transformers available for use
in the Transformer Cabinet:
An autotransformer with 480 V primary to 280 V/120 V secondary is used for the
following:
o
208 V wye to 208 V/120 V wye
o
480 V wye to 208 V/120 V wye
o
208 V delta to 208 V delta
o
480 V delta to 208 V delta
An isolation transformer with 480 V primary to 208 V/120 V secondary is used for the
following:
o
208 V delta to 208 V/120 V wye
o
480 V delta to 208 V/120 V wye
An isolation transformer with 480 V primary to 480 V/277 V secondary is used for the
following:
o
480 V delta to 480 V/277 V wye
