IVSkim the text and decide whether the following sentences are true or false. Discuss them with your partner.1 Methods of voltage regulation include varying thecurrent to the generator exciter windings andmaintaining a constant load on the generator. 2 This isaccomplished by using a current regulator. 3 Generator output frequency is regulated by keepingthe generator rotating at a high speed. 4 This is doneby mounting the generator on a APU unit. 5 The most common method of voltage control inpower generating systems is varying the current to thegenerator exciter winding (sometimes called field winding). 6 This, in turn, changes the size of themagnetic field, which changes the voltage output of thegenerator. 7 The second method of voltage regulation is tomaintain a required load on the generator. 8 This methoduses a permanent magnet on the generator rotor in placeof exciter windings, which simplifies generatorconstruction. 9 This type regulator is for use with both acand direct current (dc) power sources. 10 When magnetic fields of alternating polarity passacross the armature windings, dc voltage induction occurs. 11 Control of the voltage induced into the ac generator windings depends on five things. 12 The number of turns per winding and the number of windings are set during generator manufacture. 13 The frequency of the output voltage doesn`t depend on the speed of the generator. 14 The strength of the magnetic field doesn`t control the level of output voltage. 15 In today’s aircraft, electrical and electronic equipment don`t operate at exact frequencies and voltages. 16 Systems exposed to extreme overvoltage or off-frequencies only destroy themselves, but may start a fire during an emergency. 17 Ac generator control systems must contain circuits to protect against under voltage and overvoltage, under frequency and over frequency, and improper phase sequence. 18 The generators use an electromagnetic field rather than a permanent magnet- type field. 19 On the brushless generator, the rotating five-phase rectifiers change the ac output of the exciter to dc. 20 Dc then feeds the main ac generator rotating field, eliminating the use of brushes.
V Grammar:
|
