Specifications

9
Three-Phase Transformers Transformers used with three-phase power require three
interconnected coils in both the primary and the secondary.
These transformers can be connected in either a wye or a delta
configuration. The type of transformer and the actual voltage
depend on the requirements of the power company and the
needs of the customer.
The following illustration shows the secondary of a wye-
connected transformer and the secondary of a delta-connected
transformer. These are only examples of possible distribution
configurations, the specific voltages and configurations vary
widely depending upon the application requirements.
A
B
C
A
B
C
N
N
Wye Delta
480 Volts
277 Volts
120 Volts
240 Volts
208 Volts
A - B
B - C
C - A
A - N
B - N
C - N
480 Volts
480 Volts
480 Volts
277 Volts
277 Volts
277 Volts
A - B
B - C
C - A
A - N
B - N
C - N
240 Volts
240 Volts
240 Volts
120 Volts
208 Volts
120 Volts
480 Volts
480 Volts277 Volts
277 Volts
120 Volts
240 Volts
240 Volts