Question 1.
a.
What is power factor correction, and why is it useful?
b.
What is the effect of increasing the DC excitation current to a synchronous generator
connected to an infinite bus?
c.
How can the direction of rotation of a three-phase induction motor be reversed?
d.
Why is it impossible for the rotor of an induction motor to rotate at the same speed as that
of the magnetic field?
e.
Show that, with the aid of a phasor diagram, the power output for a synchronous
generator is given by:
$P = \frac{3V_tE_f}{X_s}sin\delta$
f.
Explain why induction motors have low power factor when they are lightly loaded
g.
Why is a synchronous motor not self-starting?
h.
When using the two-wattmeter method to measure total three-phase power, under what
conditions might one of the wattmeter readings have a negative value (assuming the
meters are connected correctly)?
i.
Alternators driven by steam turbines require only few poles to generate the required
frequency. Why is that, and why is their construction different than that of the alternators
driven by water turbines?
j.
Why is the efficiency of an induction motor so poor at high slip?
