What is 11 kV single phase?

Answer 1

for USA, Canada and other countries running a 60 Hz supply service.A 11kV single phase line is one phase of a three phase system. The three phase system voltage is found by multiplying 11kV x 1.73. The three phase primary system voltage is 19kV. A transformer with a 11 kV primary can have a secondary of 115/230 depending on the internal connections in the transformer's case.
For the UK11 kV is the standard three-phase h.v. distribution voltage in the UK, where it is a line voltage (i.e. it is the voltage measured between any pair of the three line conductors). A single-phase distribution transformer is connected between any two lines, so 'single-phase 11-kV' is simply a connection made between any two lines of an 11-kV three-phase system.

As the primary windings of three-phase 11-kV distribution Transformers are delta (3-wire) connected, the primary phase voltage is numerically equal to the primary line voltage (11 kV).