Engine Electrical Systems

What device is used to convert alternating current, which has been induced into the loops of the rotating armature of a dc generator, to direct current?

• A rectifier.
  
  

• A commutator.
  
  

• An inverter.

A certain direct current series motor mounted within an aircraft draws more amperes during start than when it is running under its rated load. The most logical conclusion that may be drawn is

• the starting winding is shorted.
  
  

• the brushes are floating at operating RPM because of weak brush springs.
  
  

• the condition is normal for this type of motor.

The stationary field strength in a direct current generator is varied

• by the reverse-current relay.
  
  

• because of generator speed.
  
  

• according to the load requirements.

   

What type of electric motor is generally used with a direct-cranking engine starter?

• Direct current, shunt-wound motor.
  
  

• Direct current, series-wound motor.
  
  

• Synchronous motor.

Upon what does the output frequency of an ac generator (alternator) depend?

• The speed of rotation and the strength of the field.
  
  

• The speed of rotation, the strength of the field, and the number of field poles.
  
  

• The speed of rotation and the number of field poles.

A high surge of current is required when a dc electric motor is first started. As the speed of the motor increases,

• the counter emf decreases proportionally.
  
  

• the applied emf increases proportionally.
  
  

• the counter emf builds up and opposes the applied emf, thus reducing the current flow through the armature.

   

Alternators (ac generators) that are driven by a constantspeed drive (CSD) mechanism are used to regulate the alternator to a constant

• voltage output.

• amperage output.

• hertz output.

What is used to polish commutators or slip rings?

• Very fine sandpaper.
  
  

• Crocus cloth or fine oilstone.

• Aluminum oxide or garnet paper.

If a generator is malfunctioning, its voltage can be reduced to residual by actuating the

• rheostat.
  
  

• generator master switch.
  
  

• master solenoid.

If the points in a vibrator-type voltage regulator stick in the closed position while the generator is operating, what will be the probable result?

• Generator output voltage will decrease.
  
  

• Generator output voltage will not be affected.

• Generator output voltage will increase.