When a rated load with 0.8 lagging power factor is supplied, the terminal voltage of a three phase star connected alternator with a certain interference is 6600 V (line-to-line value). With the same interference, the voltage developed in the open circuit is 7154 V (phase value). What will be the value of voltage regulation of the alternator?

The correct answer is option 1):(87.8%)

Concept:

The voltage regulation of an alternator is defined as the ratio of the rise in voltage when full load is removed (field excitation and speed remaining the same) to the rated terminal voltage.

% voltage regulation  \(= \frac{{{E_0} - V}}{V} \times 100\)

Where E₀ is the no-load voltage And V is the rated voltage

Calculation:

Given:

no-load induced emf (E₀) =  7154 V(phase value)

= 12391 V

Rated terminal voltage (V) =  6600 V

Voltage regulation \(= \frac{{12391 - 6600}}{{6600}} \times 100 = 87.8\)