Electrical 2; MOD 2
A motor that produces 375 watts of power is a _____ horsepower motor.
0.5
A consequent-pole motor has _____ speed(s).
2
The electrical energy required to produce 1hp of mechanical energy is _____.
746W
Most industrial motors are NEMA Design __________.
B
The NEMA frame designation for gasoline pump motors is _____.
G
The code requirements for motor disconnects are covered in _____.
NEC Article 430, Part IX
The NEC® section that covers disconnecting means for motors is _____.
NEC Section 430.109
The service factor rating is _____.
a multiplier related to the horsepower overload the motor can tolerate
The speed of a DC shunt motor is varied by _____.
altering the voltage applied to the armature or field winding
A three-phase synchronous motor is started with a(n) _____.
amortisseur winding
The full load amps (FLA) rating of a motor means the _____.
amount of current a motor will draw when operating at the nameplate voltage, frequency, and horsepower
The name of the motor part that rotates during operation is the _____.
armature/ rotor
The part of a DC motor that makes electrical contact with the commutator to provide continuous voltage is the _____.
brushes
Which of the following types of single-phase induction motors has a start winding that is switched out of the circuit after the motor starts?
capacitor start
o determine the horsepower rating of a motor that is already installed and in place, _____.
check the nameplate data
motor that has three sets of three leads with continuity between the wires in each set is a _____-connected motor.
delta
The NEMA Dimension D of a motor is the _____.
distance from the motor feet to the centerline of the shaft
Reconnecting a running motor to act as a generator is known as _____.
dynamic braking
The principal reason for developing the brushless DC motor was to _____.
eliminate commutator problems
The letters FLA on a motor nameplate stand for _____.
full-load amps
The method of braking in which DC is applied to the motor windings after AC is removed is known as _____.
injection braking
The synchronous speed of a motor is determined by frequency of the applied voltage and the _____.
number of magnetic poles
The speed of an induction motor depends on the power supply frequency and the _____.
number of poles
The two primary types of motor enclosures classified by NEMA are _____.
open and totally closed
what is on a motor nameplate?
power factor, efficiency, torque, and current are at rated voltage and frequency
Large DC motors require that a starting _____ be placed in series with the motor armature.
resistance
The starting torque characteristics of a wound-rotor motor are defined by _____.
rotor resistance
An open AC squirrel cage motor that makes use of form-wound coils and an insulation system is known as a(n) _____.
sealed windings
When there is a wide variation in both torque and speed requirements, such as a blower or a hoist, use a _____.
series DC motor
The multiplier to the nameplate horsepower rating is called the _____.
service factor
Given the speed and torque characteristics of shunt and series DC motors, which one would be the better suited to the varying loads of an escalator?
shunt
The DC motor that provides good speed control but low starting torque for large loads is the _____ motor.
shunt
In three-phase motors, the rotor most commonly used is the _____.
squirrel cage rotor
A synchronous motor uses a(n) _____ to obtain starting torque.
squirrel cage winding
The NEMA design letter (A-F) refers to the motor's _____.
starting torque characteristics
The name of the stationary motor part that produces the magnetic field during operation is the _____.
stator
The speed on a multiple-winding motor is normally changed by _____.
switching contacts in the motor controller
The two classes of AC motors are _____.
synchronous and induction
Counter- electromotive force opposes
the applied voltage
The minimum starting voltage is the _____.
the minimum voltage at which the motor will start without drawing excessive current
To protect the motor from overloads and starting failures, use a _____.
thermal protector
The angular difference between the rotor pole and the stator pole of an operating synchronous motor is called the _____ angle.
torque
A pipe-ventilated motor is classified as _____.
totally enclosed
A consequent-pole motor has _____.
two speeds
The shaded-pole motor is used in _____.
very low horsepower applications
An insulation resistance test can be used to determine _____.
whether a motor is damp
Which of these AC induction motor configurations would be selected for a variable-speed application?
wound rotor
According to the NEC Section 430.22, when a single motor is supplied by a branch circuit, the ampacity must not be less than _____.
125% of the full load current
You would be unlikely to find a capacitor-start motor in a size larger than _____ horsepower.
10
motor controller must have a rating of no less than _____% of the motor full load current.
100
All motors must have a thermal protector if their voltage rating is greater than _____.
1000V
The rpm of a 60Hz motor with two poles is _____.
3600 rpm