Flashcards in DC Motors Deck (26):
Which of the following is the best description of the DC motor
A machine that converts electrical to mechanical energy
What two factors determine the torque developed by a DC motor
Field and Armature flux
With a rheostat connected to the Armature blank resistance is used at the base speed
To adjust the speed of the shunt motor above the base speed we control current in the ...
If you notice arcing at the brushes of a DC shunt motor you could adjust the brushes blank the motors direction of rotation to reduce the arcing
What is the best way to reverse the direction of a DC motor
Reverse the Armature connections
When a DC motor is producing torque which of the following is a constant
Number of Armature conductors
The direction of rotation of a series motor could be reversed by inner changing the leads from the supply battery
Using the motor speed characteristic curve chart select the letter of the curved up longs to each motor connection compound motor ,series motor, shunt motor
Series is the lowest, compound motor is the middle, shunt is the top
What is the effect on the torque of a DC Shunt motor in the field current is kept constant an Armature current is halved?
Torque is halved
Which of the following symptoms would suggest improper operation of a DC motor?
High operating temperature, sparking at the brushes, excessive vibration, all the above
Which of the following is a typical fault with the DC motor?
Shorted windings infield or Armature, open winding infield or Armature, grounded winding infield or Armature all the above
Which of the following test equipment is most effective in conducting insulation test?
A shorted coil can be discovered with which of the following maintenance procedures?
Which of the following will result in excess of arcing at the brushes?
Broken brush tension spring, incorrect interpole polarity, I communicator Mica, all of the above
Series windings consist of blank turns of blank wires
Few turns large wires
Shunt windings consist of blank turns of blank wires
Many turns small wires
The DC Shunt motor shown below will rotate blank
The CEMF generated by a DC motor is proportional to what two variables?
Flux and speed
The Armature current of a DC motor operating at the speed is limited by what two variables?
CEMF and Armature resistance
What is the best feature of a shunt motor?
What is dangerous to do to a shunt motor?
Open shunt unsafe speed
What is the best feature of the series motor?
High torque starting
What is dangerous to do to a series motor?
Must be coupled directly not with a belt or chain
What is the danger of misconnecting accumulative compound DC motor as a differential compound DC motor?
Motor will reverse