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ELECT 218 AC/DC Motors midterm
Terms in this set (84)
The methods used to determine motor torque are _________________, current measurements, and dynamometer.
An application for measuring motor torque is to determine if the motor is ____________________.
A dynamometer is basically a DC _________________________.
As motor torque increases on an electric motor, ___________________ also increases.
A ___________________ is directly coupled to a motor shaft and held by a spring scale.
Operating a motor in an overload condition results in a shortened _________________________.
service life for the motor
The rotational speed of a motor is measured in ______________.
Revolutions per minute (RPM)
The device that is most often used to measure motor speed is the _______________________.
A ____________________ tachometer determines motor shaft speed by counting the number of times a reflective tape on the motor shaft passes through its light.
One of the applications of measuring motor speed is to check for positive ______________________ condition of an AC motor.
A tachometer __________________(can/cannot) be used to check the performance of speed control.
__________________ is a measure of the turning effort caused by a force acting on a part that rotates.
The S.I. units of torque are
Newton Meters (N-M)
Torque is increased by either applying the force further from the ______________ or by increasing the force applied.
The ___________________ on an electric motor is the amount of torque that the motor must generate at its shaft to overcome the resistance caused by the device that is driven.
To turn a load, the electric motor must generate a torque that __________ the torque requirements of the load.
on a drive belt system, the torque that is delivered to the load depends on the _________________ratio.
The effect that was the gear or pulley ratio has on speed is exactly ______________to the effect on torque.
Torque is developed in an electric motor because of the interaction of different __________________.
A DC shunt motor has its field windings connected in ___________________ with the armature.
An advantage of the self-excited DC shunt motor is that it is able to ___________ its speed over a wide load range.
A DC shunt motor _________(does/does not) provide high starting torque.
A DC shunt motor will not ________ if there is no load connected to it, unlike a DC series motor.
Major components for all motors:
Stator, rotor/armature, shaft. DC motors: commutator, brushes
When the shunt field is connected to the same power supply as the armature, it is called a _______ shunt field
The ________ windings have much less resistance than the field windings.
When a separate power supply is used for a shunt field, it is called a _______ shunt field.
One of the major advantages of a separately- excited shunt motor is that the motor can be operated________ its rated name-plate speed.
When a DC motor is connected in a separately- excited configuration, as the field current is decreased, the motor speed_________ (increases/decreases)
The direction of rotation on a DC shunt motor can be reversed by either reversing the field connections or the ________ connections
The process of reducing the field current of a separately- excited shunt motor is called________
The maximum speed of a self-excited shunt motor is determined by the_______
A DC _______ motor is a motor with a field connected in both series and in shunt with the armature.
A DC compound motor provides _______ (higher/lower) starting torque than a shunt motor.
A DC compound motor provides better _______ control than a series motor.
If the series and shunt windings are connected in a compound motor so that their magnetic fields have the same polarity, the motor is configured as a ________ compound motor.
The _______ compound motor has very few applications and its avoided for the most part
The only sure method to reverse the direction of rotation on a cumulative compound motor is to reverse the ________ connections.
Electric motors rely on the principle of _______ to convert electrical power into mechanical power.
The three categories of electric motors are DC, AC and _______ motors
There are ______ rules of safe dress around motors.
Always _____ a motor from electrical power before installing, coupling, or servicing it.
A motor must be properly ________ to the load it is driving.
Dirt buildup can cause excessive________ which can reduce the life of a motor.
_________ clothing should always be worn when working around a motor.
Get someone to help move a motor or mount an electric motor if it is too _______ to handle alone.
An electric motor must be kept ______ and dry.
make sure that no _____ parts or tools are left around a motor when it is in operation.
Installing the wrong motor can cause _______ to the motor and the load its coupled to.
The ________ are the stator of the DC motor.
The primary purpose of the __________ are to reduce sparking between the brushes and the commutator.
The rotation of an electric motor is created by the interaction of two different ___________.
The 3 basic motor configurations are: _________ , shunt and compound.
A DC series motor has the field windings connected in _________ with the armature.
________ is a rotary force produced by a motor.
The major advantage of a DC series motor when it is operated, a condition known as ___________ will occur.
The easy access to ______ often leads to the selection of an electric motor for application.
Since a motor has moving parts, it must be ______ on a regular schedule in order to ensure longer life and proper operation.
The _______ is the stationary part of an electric motor.
The rotor is the _______ part of an electric motor
One application of a DC series motor is a ________ , which requires high starting torque to lift items.
To reverse the direction of rotation on a DC motor, either reverse the ________ connections or the armature connections, but not both.
Reversing the ______ leads to a DC motor will not affect the direction of rotation.
The standard direction of rotation for all Amatrol- supplied motors is _________.
The shaft rotation direction can be determined by observing the motor from the end _______ the shaft.
Using both methods to reverse the direction of rotation of a DC motor at the same time ________ (will/will not) change the direction of the rotation.
The ________ method will not work with all DC motor configurations.
___________ is the rate of doing work.
The U.S. Customary power unit for motors is _________
horse power (Hp)
The S.I. power unit for motors is __________
Efficiency of a motor is the ratio of the _______ power to the input
On a DC motor, the current used to calculate the input power is the ________ current.
A motor converts ___________ power into mechanical power.
The __________ of a motor are a deciding factor in the selection of the proper motor for an application.
Four characteristics of a motor that are used for selection are speed, ________ , power output, and efficiency.
Many motor characteristics can be determined using the __________ for a motor.
Motor power is given in kilowatts in the S.I. system and _____ the U.S. customary system.
horse power (Hp)
Efficiency is the ratio of motor _________ to electrical input motor.
Motor efficiency is given as a(n) ___________
The _______ torque is the initial torque necessary to accelerate a load to full speed.
_________ and torque are the two performance characteristics of a motor that are most often used to select a motor for an application.
A ______ configured DC motor usually provides the highest starting torque.
Speed ______ refers to the motor's ability to maintain speed as the load increases.
A _______ configured DC motor usually provides the best speed regulation.
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