DC Motors
What is Torque?
The turning force of a motor.
What is motor slip?
The difference between the speed of the rotating magnetic field and the speed of the rotor.
A single phase motor contains two windings. The ______ winding and the _______ winding .
Start; Run
By what percent of the motors current must the branch circuit conductors be sized at?
125%
How can the direction of rotation on a DC motor be reversed?
By reversing the two armature leads.
How many degrees apart is each phase from one another in a 3-phase system?
120 degrees.
What is an advantage of a single phase motor over a 3-phase motor?
Single phase motors can be used in residences where only single phase power is available.
What NEC table gives FLC data for DC motors?
Table 430.247
The component that supplies power to the armature via the commutator.
The brush assembly
Name a disadvantage of friction braking.
Brake pad wear.
What causes the start winding to be disconnected from the circuit after motor start?
A centrifugal switch
When sizing the motor overload, you should always use the data provided _________
On the motor nameplate.
The _________ is the part of the motor that contains the permanent magnets.
Stator
How can the direction of a 3-phase motor be reversed?
By reversing any two of the three leads(Commonly T1 and T3).
What is the component that rotates with the rotor?
The shaft.
At what percent of the motor may a dual element, time-delay fuse be sized at?
175%
What are the two types of DC motors?
DC Series and Shunt motors.
What is dynamic braking?
A method of slowing a motor by disconnecting line power and shorting the motor leads across a braking resistor.
How many bearings does a motor contain?
2
Name the two types of motor starters.
NEMA; IEC