ac dc motors

In the split-phase motor, how many distinct electric-current phases exist in the stationary part of the motor when the rotational speed of the motor's shaft is between 90% and 95% of its rated full speed? ____________________

1

A(n)1 -----2 set is a motor and a generator with shafts connected used to produce the required DC power to excite the rotor of a 3-phase synchronous motor.

1 motor 2 generator

Typical types of circuit faults are an 1 circuit, a 2 circuit, or a ground fault.

1 open 2 short

In a split-phase motor, the speed of the rotating magnetic field (in the stationary part of the motor) is determined by the frequency of the AC input and by the number of poles in the stationary part of the motor. This speed is called 1 the speed of the motor; and, the difference between the speed of the shaft and the speed of the rotating magnetic field is called 2

1 synchronous 2 slip

Generally any voltage above ______ volts is considered dangerous.

30

If the motor nameplate shows 1725 rpm as the full-load speed, the stator has ______ poles.

4

In a split-phase motor, the phase difference between the current in the start winding and the current in the run winding is about 300. Putting a capacitor in series with the start winding makes this phase difference close to ______0.

90

_________________ current flow is a description of current flow as the flow of positive charges from the positive terminal to the negative terminal of a power source.

Conventional

__________________ current flow is a description of current flow as the flow of positive charges from the positive terminal to the negative terminal of a power source.

Conventional

________________ is when a motor turns ON and OFF more frequently than the motor design allows.

Overcycling

_______________ is the condition where a magnetic core has substantially all the magnetic domains aligned with the field and any increases in current no longer result in a stronger electromagnet.

Saturation

--------- is the condition when a 3-phase motor is operating on only one phases because one line is lost.

Single phasing

A(n) _____________ is the process where the centerlines of two machine shafts are placed within specified tolerances.

alignment

A(n) _____________ misalignment is a condition where one shaft is at an angle to the other shaft.

angular

That part of a DC motor which consists of a shaft, a laminated and grooved core, windings, and a commutator is called the ____________________.

armature

[1] reaction is the distortion of the magnetic fields that happens when a current-carrying wire is placed within a fixed magnetic field.

armature

A(n) _________________ load, or thrust load, is a load applied parallel to the rotating shaft.

axial

A(n) ____________ bearing is a rolling-contact bearing that permits free motion between a moving part and a fixed part by means of balls confined between inner and outer rings.

ball

A(n) _________________ is a machine component used to reduce friction and maintain clearance between stationary and moving parts.

bearing

The _____________ of a DC motor require the most maintenance attention

brushes commutator

In most split-phase and capacitor motors, the start winding is de-energized when the motor reaches 75% to 85% of full speed. The --------- is often used to disconnect the start winding before the motor reaches full-rated speed.

centrifugal switch

A(n) _________________ universal motor is a universal motor with extra windings added to the field poles.

compensated

A(n) ________________-wound motor is a DC motor with both a series field winding and a shunt field winding.

compound

A synchronous -------- is a synchronous motor operated at no load in order to provide power factor correction.

condenser or condensor

Motor _________________ is a measure of the effectiveness with which a motor converts electrical energy to mechanical energy.

efficiency

A(n) __________ drive is a synchronous mechanical drive system that uses the meshing of two or more gears to transfer motion from one shaft to another.

gear

The is the ratio between the diameter of the drive gear and the driven gear.

gear ratio

3-phase ____________ motors are the most common motors used in industrial applications because they operate for many years with little or no required maintenance.

induction

The _______________ are connected in series with the armature windings and are used to reduce sparking at the brushes of larger DC motors.

interpoles

conductor rule is an explanation of the direction of a magnetic field around a conductor relative to the direction of the current in the conductor, where a left hand is used to illustrate the relationship.

left hand

A(n) ------- induction motor is an AC motor that uses induction to create linear movement.

linear

A motor defect is an imperfection accidently created during the _________________ of the motor that impairs its use.

manufacture manufacturing building making

A(n) ______________ meter is used to measure insulation deterioration on various wires by measuring high resistance values during high-voltage test conditions.

megohm megohmmeter

A(n) ____________ bearing is a rolling-contact roller-type bearing with long rollers. of small diameter.

needle

When installing and adjusting brushes, the brushes must be set to brush _____________ in order to avoid excessive arcing, and other problems.

neutral

The brush- [2] position is the proper position of the brushes where commutation can occur with minimal arcing/sparking and induced voltage in the armature coils.

neutral neutral

A(n) ______________-excited synchronous motor operates at leading power factor. This is the normal operating condition of a synchronous motor.

over

_______________ is a measure of the ability of a material to conduct magnetic flux.

permeability

A(n) -------- field frequency relay is a relay used to apply current to the DC field windings of a synchronous motor and to remove the discharge resistor from the starting circuit.

polarized

The ________________ rating is the amount of power a motor can deliver to a load.

power

There are two sets of windings in the stationary section of most split-phase and capacitor motors. The main winding, which is always energized during the operation of the motor is called the ______ winding.

run

A(n) ___________-wound motor is a DC motor that has the field winding connected in series with the armature.

series

When a compound-wound DC motor loses it's shunt field it becomes a [1]-wound motor.

series

rating is a multiplier that represents the amount of load, beyond the rated load, that can be placed on a motor without causing damage.

service factor

A(n) ______________-motor uses closed-loop feedback signals from an encoder to provide position and speed control.

servo

A(n) _______________ circuit is a circuit in which current bypasses the normal path of current flow, with little to no resistance.

short

The ________________ rating of a motor is the approximate speed at which the rotor of a motor rotates when delivering rated power to a load.

speed

The advantage of a shunt-wound DC motor is its relatively good regulation.

speed

The disadvantage of a series-wound DC motor is its relatively poor [1] regulation.

speed

Reversing the __________ winding is the standard method used in industry for reversing the direction of rotation of a single phase motor.

start

The advantage of a series-wound DC motor is its relatively high [2].

starting torque

AC split-phase and capacitor motors are built with two main sections. That section which consists of a shaft, a laminated and grooved core, and a squirrel-cage-type "winding" is called the rotor, while the section which consists of a motor frame, laminated cores attached to the frame, and field-type windings is called the

stator

windings are stationary windings used to produce the magnetic field in a motor.

stator or Field

A motor is a motor that uses discrete voltage and current pulses to control the movement of a load.

stepper

A(n) ______________________ motor is a motor that rotates at exactly the same speed as the rotating magnetic field of the stator.

synchronous

A(n) bearing is a roller bearing having tapered rollers.

tapered rollers

A(n) is the dimensional change in a substance due to a change in temperature.

thermal expansion

Compared to the simple, split-phase motor, the capacitor motor has a higher ___________ at start-up.

torque

A motor's nameplate _____________ rating is the optimal voltage that should be connected to the motor for best operating performance.

voltage

Common types of power problems in addition to single phasing are: phase unbalance, voltage unbalance, and -------- surges.

voltage

In a typical dual--------- motor, the run winding is split into two sections.

voltage