Motors Final Review pt 1/4 Flashcards
The ability of a material to conduct magnetic flux is called ____.
Permeability
The ability of a material to retain residual magnetism is called ____.
Permeance
With a DC motor, a ____ is used to reverse the current direction, therefore, keeping the current flowing in on direction (DC) through the windings to keep the polarity correct in order to interact with the main fields.
Commutator
Mutual Inductance is the ability of an inductor in one circuit to ____ a voltage in another circuit or conductor.
Induce
Similar to an AC motor, a _____ is the fixed part of an alternator that supplies a magnetic field though the field windings.
Stator
A DC ____ operates on the principle that voltage is induced in a coil of wire when the coil is rotated in a magnetic field.
Generator
The three factors that control the output of an alternator are :
- length of the wire2. speed of the rotor3. strength of the magnetic field
The ____ output of an alternator or generator must be between +5% & -10% of the requirements for the load(s).
voltage
If the total number of coils wound in a three phase stator is 36, then each phase contains ____ coils.
12
The ____ us a cylindrical bar used to carry the revolving rotor and transfer power from the motor to the load.
Motor shaft
The synchronous speed of a 60-Hz, 4 pole motor is ____ .
1,800 RPM120 x 60 / 4; 120 x Hz / P (# of poles)
____ torque is also referred to as breakaway torque or starting torque.
Locked Rotor
Motor power is rated in ____ or ____.
Horsepower / watts
____ is calculated by dividing output power by input power.
Motor efficiency
____ and ____ are used to connect the rotor of a wound-rotor motor to an external set of secondary resistors.
Brushes & slip rings
When the speed of a motor changes, the horsepower and torque required at the new speed may be ____.
Higher/Lower/The same
The construction of the ____ in a wound rotor motor is identical to that of the ____ motor.
Stator / squirrel cage
The rotor is mounted on a ____ that is used to transfer power to the load.
shaft
Three phase AC power is generated by rotating coils through the ____.
Magnetic field
The rotor’s magnetic field and the stator’s magnetic field interact to create ____.
torque
The ____ is the stationary part of an AC motor. It consists of a laminated iron core and windings that convert electrical energy to the energy of a magnetic field.
Stator
The speed of a wound rotor motor may be reduced by increasing the ____ of the rotor circuit while the motor is running, in order to reduce the current in the rotor windings.
resistance
The windings of a 3-phase wound rotor motor are located ____ electrical degrees apart in the slots of the stator.
120360 / # of phases
The rotor winding coils of a wound rotor motor are made up of ____.
insulated copper conductors.
When troubleshooting a three phase motor, the motor windings should be checked for any opens or shorts by using a DMM (digital multi-meter) set to measure ____.
resistance
