Motors II exam review
Polarity
A DC motor can be reversed by changing this on either the armature winding or the field winding
Split phase motor
A capacitor start motor operates much the same as this motor, centrifugal switch that opens at approximately 60 to 80% of full load speed
Capacitor run motor
A permanent split capacitor motor is also known as this type of motor
"Fused device"
According to 430.52, what type of device is a motor short circuit protector?
0 to 6000 A
Cartridge fuses are available with amperage ratings in a range from...
Three types of wound rotor motor regulators
Drum switch, three pole rheostat, silicon controlled rectifier's
True
Fuses themselves do not need to be maintained. The fuse holders, terminations, and disconnects should be inspected regularly
Small amounts of overcurrent
Generally, motor overload protection only protects against...
Drum
If a capacitor start motor is to be reversed often, then one of these switches or a foot switch can be used to reverse the current through the start with respect to the run windings
Use the next size up
If starting current is a problem, do this...
Split phase motor
One of these motors is a single phase AC motor that includes a run winding and resistive start winding used in applications were starting is easy, such as fans, business machines, machine tools, and centrifugal pumps
On a 3phase wound rotor motor, ——- is the conductor, and ——- ——is the insulator
Pigtail....brush holder
Overcurrent protection
The NEC requires this of all motor installations
Overcurrent
The function of an OCPD is to protect branch circuit conductors, control equipment, and motors from damage caused by this
Commutator
The function of this device is to keep armature windings in the correct polarity to interact with the main fields of a motor
Armature windings
The inner polls are connected in series with these
Single phase motors
These motors do not have a rotating magnetic field and are named for the method used to develop the rotating magnetic field
Time delay fuses
These type of fuses do not allow over current to exist, to avoid Nuisance tripping due to equipment start up characteristics
Short circuit condition
This condition causes the current to rise hundreds of times higher than normal at a very fast rate
Shaded pole
This is a short circuited winding, which consist of a single term of copper wire and ask on only a portion of the stator windings
Overload
This occurrence in the motor is caused by a load that exceeds the full loading rating of the motor
Ground fault
This occurrence is an unintentional connection between an ungrounded conductor and any grounded raceway, box, enclosure, or fitting
DC generator
This operates on the principle the voltage is induced in a coil of wire when the coil is rotated in a magnetic field
Thermal magnetic breaker
This type of circuit breaker uses a buy metal strip connected in series with the load to open circuit
Squirrel Cage
This type of motor has conductor bars in it. Conductor bars are attached to a shorting ring. On a wound rotor motor... The rotor is made from insulated copper windings that are not shorted
Series wound DC motor
This type of motor has the highest starting torque
Thermal overload relay
This type of overload relay uses it was just a heating element to open a set of contacts
Capacitor motor
Typical applications of these motors include fairly hard to start loads, like refrigerators, air conditioners, air compressors and some power tools
Motors, motor control apparatus, and motor branch conductors
What are overload devices intended to protect?
Add Resistance
What do we do to create higher torque in a three phase wound rotor motor?
you have to physically remove the rotor
What do you do if you want to change the direction of a shaded pole motor
You have to flip-flop one of the two windings
What do you do if you want to change the direction of a split phase motor?
Switch the two start leads in the circuit
What do you do to cause the rotor of a single phase motor to turn in reverse?
Reduced by half
When the dual voltage single phase motor is reconnected for the higher voltage (115 to 230 V), current is reduced by?
We're OCP power loss would cause a greater Hazzard... Like fire pumps
Where are the provisions for overload protection not required?
Locked in place
With rotation is not possible because of the stators field and the rotors field or equal or parallel to one another, the rotor is this...
6 times
for small motors not covered by the NEC, locked rotor current shall be assumed to be this many times the FLC
line to ground fault
what condition is not protected by motor overloads