Question

A 9KVA,208V, three phase, Y-connected synchronous generator has a winding resistance of 0.10hms/ phase and a synchronous reactance of 5.6ohms/ phase. Determine its voltage regulation when the power factor of the load is

(a) 0.8pf lagging
(b) 1.0pf
(c) 0.8pf leading

Answer 1

Voltage regulation of a three-phase synchronous generator depends on the internal generated voltage versus terminal voltage and can be calculated for different power factors such as 0.8 lagging, unity (1.0), and 0.8 leading.

Step-by-step explanation:

To calculate the voltage regulation of a three-phase synchronous generator, we use the formula for voltage regulation which is ((Ef - VL) / VL) × 100%, where Ef is the internal generated voltage and VL is the terminal voltage. The voltage regulation changes with the power factor of the load.

For a synchronous generator with a given winding resistance (R) and synchronous reactance (Xs), we can calculate Ef for different power factors using the per-phase values and the phase impedance triangle, which takes into account the impact of the lagging, unity, and leading power factors on the angle between the generator voltage and the current.

The voltage regulation for different power factors can then be calculated by comparing the difference between the internal generated voltage Ef and the line voltage VL for the following scenarios:

1. 0.8 power factor lagging
2. 1.0 power factor (unity)
3. 0.8 power factor leading