EGSA Voltage Regulation and Excitation 2

Question 1

What does a negative voltage regulation value indicate about a generator's performance?

Accepted Answer

Terminal voltage rises from no-load to full-load

Answer

Negative voltage regulation means the terminal voltage increases as load is applied, which is characteristic of generators with leading power factor loads.

Question 2

In a brushless excitation system, what component rectifies AC exciter output to supply DC to the main rotor field?

Accepted Answer

A rotating diode assembly mounted on the rotor shaft

Answer

In brushless exciters, rotating rectifier diodes mounted on the rotor shaft convert AC output of the exciter armature to DC for the main generator field without brushes or slip rings.

Question 3

A generator is operating at rated voltage with no load. When full resistive load is applied, voltage drops 8% before the AVR corrects it. This initial dip is primarily caused by:

Accepted Answer

Exciter time constant delay

Answer

The initial voltage dip before AVR correction is largely due to the excitation system's time constant—it takes finite time for field current to change and terminal voltage to recover.

Question 4

What is the purpose of a derivative (rate) feedback signal in an AVR?

Accepted Answer

To improve transient response and dampen voltage oscillations

Answer

Derivative feedback responds to the rate of voltage change, helping to dampen oscillations and speed up transient response after sudden load changes.

Question 5

Reactive droop compensation in an AVR causes generator terminal voltage to:

Accepted Answer

Drop proportionally as reactive load increases

Answer

Reactive droop causes terminal voltage to decrease as reactive (lagging) load increases, enabling stable reactive load sharing between parallel generators.

(EGSA) Electrical Generating Systems Association Certified Practice Test

(EGSA) Electrical Generating Systems Association Certified Practice Test

EGSA Voltage Regulation and Excitation 2