Power Generation Flashcards
What is a leading power factor, and what component causes it?
A leading power factor implies that the current leads the voltage, and it is caused by a capacitor. This gives a negative power factor, a negative value for the imaginary component of impedance, and a positive component for the complex part of current.
What is a lagging power factor?
A lagging power factor is caused by an inductor, and is when the current waveform lags the voltage. This can be seen by a negative imaginary part to the current, or a positive imaginary component to the impedance and reactive power. A lagging power factor is positive.
How do you convert from a phase diagram to an operating chart?
Scale sides by 3V/Xs (and add prime-mover and stability limits)
Where is the rotor limit on an operating chart?
A semi-circle traced around A by the line 3VE/Xs
Where is the stator limit on a generator operating chart?
A semi-circle traced around the point O (end of the scaled V line) by the line 3VI
Where should the stability limit be drawn on a generator operating chart?
The true limit is a line vertically up from A (where delta = 90) since this is where Torque drops if more power is demanded. A practical limit should be drawn at a lower delta angle, but this is beyond the scope of the course so the vertical line will suffice.
