Page 556 - Basic Electrical Engineering

A high value of voltage regulation means that there is a large change in the

terminal voltage when load is applied to the transformer, which is not
desirable.

The expression for voltage regulation in terms of load current, load power
factor, and transformer circuit parameters can be found from the simplified

equivalent circuit of the transformer. For convenience, we will consider the
approximate equivalent circuit of the transformer with primary circuit
parameters referred to the secondary side as shown in Fig. 6.17. The phasor

diagram relating the various quantities has also been shown. R″ and X″ are
e
e
the equivalent resistance and reactance, respectively, of the transformer
referred to the secondary side.

Figure 6.17 (a) Simplified equivalent circuit of a transformer; (b) phasor diagram; (c) use of the
phasor diagram for calculation of the voltage drop

The equation relating E and V is
2
2