Module 1 Flashcards
the rotating part of a motor or generator
Rotor
the stationary part of a motor or generator
Stator
the allowable overload of a general-purpose motor
Service factor
the difference between a motor’s synchronous speed and its operating speed
Slip speed
the production of a rotating magnetic field by using two stator windings with a different impedance to create a difference in phase
Phase splitting
the speed of the rotating magnetic field in an induction motor
Synchronous speed
What is the name for the rotating part of a motor? For the stationary part?
Rotor; Stator
The end plate bearings support the _____ and keep it centered within the _____.
Rotor; Stator
Slip speed is the difference between a motor’s _____ speed and its _____ speed.
Synchronous; Operating
Can a standard motor made by one manufacturer be replaced by the same standard motor made by another manufacturer?
Yes
AC motors are designed to operate at +- _____% of their rated potential difference and +-_____ % of their rated frequency.
10; 5
What cools the windings in an open motor?
Air
How long can most motors run without overheating?
Continuously
Which rotates faster in an induction motor, the magnet or the disk?
Magnet
Can a symmetrically wound single phase induction motor start by itself?
No
In an induction motor, a potential difference is induced in the _____ by the _____ of the stator.
Rotor; Magnetic field
Single-phase induction motors are noisy, because the rotating magnetic field _____.
Pulsates
If two identical windings are connected to a single-phase source, will their combined magnetic field rotate?
No
In a motor or generator, how far must a conductor move in order to complete one cycle?
Past two poles
To calculate the synchronous speed of an induction motor, you need to know the _____ of the power supply and the _____ in the motor.
Frequency; Number of poles
What devices may be used for disconnecting the start winding in a single-phase induction motor?
Centrifugal switch
Magnetic relay
Thermal relay
A standard split-phase motor is used for applications that require _____ starting and _____ operating periods.
Frequent; Long
Which of the following is not part of a rotor?
a. Core
b. End plates
c. Shaft
d. Squirrel cage
b. End plates
All the following are open motors, except the ____ motor.
a. drip proof
b. splash proof
c. waterproof
d. weather-protected
c. Waterproof
Which kind of motor has one or more short circuited auxiliary windings that are displaced from the main winding?
c. Shaded-pole motor
What is the NEMA designation for a motor having normal starting torque, normal starting current, high breakdown torque, and low slip?
a. A
b. B
c. C
d. D
a. A
The maximum torque a motor can produce without an abrupt decrease in speed is called its _____ torque.
Breakdown
If two identical windings are connected in parallel to an ac source the currents in the windings will both _____ the potential difference.
Lag
The service factor of a motor is defined as the
Allowable overload
In order to complete one ac cycle, a conductor must move
Past two magnetic poles
According to Fig. 1-3, all standard motors with frame number 184T have a maximum base width of _____ in.
9
What is the synchronous speed of a six-pole motor running on power at 50 Hz.
1000rpm
