Module 7745 Chapter F

Which of these statements is incorrect with respect to AC generators and DC generators?

• An AC generator is simpler in construction

• A DC Generator is not as efficient

• A DC Generator has a better power to weight ratio

• The transmission of AC power is more efficient

Which of these statements is not an advantage of a Stationary Armature over a Rotating Field System.

• The stator provides a greater space for more armature windings, therefore more output power can be generated

• The output windings can be distributed around the stator making them easier to keep cool

• The output windings are easier to insulate for higher induced voltages

• The rotating field requires minimal current to energise the field; so only a small commutator and brushes are necessary

• Construction is simpler

Which of these statements is incorrect with regard to a Cylindrical Pole Rotor

• It is used for high Speed applications

• It has a large diameter in comparison to its length

• The rotor has two poles

• It has a steel rotor

Which of these statements is incorrect with regard to a Salient Pole Rotor

• It is used for High Speed applications

• It has a large diameter in comparison to its length

• The rotor has any even number of poles

• The poles are laminated and hold the field windings

What two properties below are essential for effective slip rings.

Select 2 answers

• High electrical resistance

• Low electrical resistance

• High coefficient of friction

• Low coefficient of friction

Which of these statements is not an advantage of a three phase AC generator?

• The stator space is better occupied by three phases, producing a greater output.

• The mechanical input power to the generator is better balanced and not pulsing.

• The three phase output produces a rotating magnetic field, which can be utilised by three phase induction motors.

• The 3 phase output is a balanced system ideal for efficient load sharing over an AC power distribution system.