dc/ac drives chapter 4,5,6

True

A locked rotor is the condition in which a motor is loaded so heavily that the motor shaft cannot turn.

Armature

A(n) ____ is the rotating part of a DC motor.

True

Autotransformer starting is a motor starting method that uses a taped 3 phase autotransformer to provide reduced-voltage starting.

True

Fans and pumps are typically classified as variable torque/variable horsepower loads.

True

Humidity is considered an environmental condition that affects the operation of a motor.

True

Magnetic motor starters include high-power contacts for switching a motor ON and OFF and typically include auxiliary contacts that are used in the control circuit.

electric motor drives

Most ____ provide manual control functins for starting, stopping, jogging, reversing, speeding up, and slowing down directly from the keypad.

Less

Motors that are not fully loaded draw ____ current than rated nameplate current.

False

Reduced-voltage starting of large horsepower motors typically causes problems in power distribution systems.

False

Some electric motor drives allow control functions to be controlled through standard communication ports such as RS-202C ports.

False

Temperature rise is the temperature of the air surrounding a piece of equipment.

Memory

____ are also known as holding or sealing circuits.

Flexible

A(n) ____ coupling allows a motor to operate the driven load while accommodating for a slight misalignment between the motor and load shafts.

Open Motor Enclosure

A(n) ____ is a motor enclosure with openings to allow passage of air to cool the windings.

Magnetic

A(n) ____ is a starter that has an electrically operated switch (contactor) and that includes motor overload protection.

starting

The industrial standard for reversing a 1 phase motor is to reverse the ____ winding.

True

The most common belt used for power transmission is the V-belt.

True

The nameplate of a motor includes the name of the manufacturer.

converter

The section of an electric motor drive that converts AC voltage to DC voltage is the ____ section.

True

The speed (rpm) of a DC motor is proportional to the voltage applied to the motor.

Poles

The speed of an AC motor is determined by the number of ____ in the motor and the frequency of the supply voltage.

manual motor starting

The traditional methods used to provide reduced-voltage starting of large horsepower motors include all of the following except ____.

False

The voltage of a control circuit is higher than the rating of the motor in most motor control circuits.

False

The wires extended from the series coil of a DC motor are marked A1 and A2.

splashproof

Totally enclosed motor enclosures include all of the following except ____.

three

Transistors are ____-terminal electronic switching devices that control current through the device by referencing the amount of applied voltage to the base.

Solid State

Transistors, silicon-controlled rectifiers, triacs, and alternistors are used as ____ switches.

Field Winding

A DC permanent-magnet motor uses magnets, not a coil of wire, for the ____.

True

A DC shunt motor is a motor with the field connected in parallel with the armature.

True

A pigtail is an extended, flexible connection or braided copper conductor.

False

A rotor is the stationary part of an AC motor that produces a rotating magnetic field.

True

A separately excited shunt field is a shunt field connected to a different power supply than the armature.

False

A shaded-pole motor is an AC motor that has running and starting windings.

Delta

A(n) ____ 3 phase motor has each phase wired end to end to form a completely closed loop circuit.

Motor Control

A(n) ____ circuit is a circuit that provides control functions such as starting, stopping, jogging, direction of rotation control, speed control, and motor protection.

False

Belt deflection must equal 1/16" per inch of shaft center-to-center distance.

False

Continuous duty cycle motors are marked INTER on the nameplate of a motor.

United States

In (the) ____, 60 Hz is the standard power source line frequency.

False

Line frequency is the number of complete electrical cycles per minute of a power source.

True

Line frequency is the number of cycles per second of the supplied voltage.

True

Locked in step is a motor condition that occurs when the field of the stator and the field of the rotor are parallel to one another, not allowing the shaft to rotate.

four

Motors with base-to-shaft center distances 3 1/2" or greater have a three- or ____-digit frame number.

True

Moving a motor or placing shims under the feet of a motor often corrects alignment problems.

IEC

NEMA is primarily associated with equipment used in North America and the ____ is primarily associated with equipment used in Europe.

False

National Electrical Code 400.7 specifies the minimum information that motor manufacturers must provide on the nameplate of a motor.

True

Placing contactors and soft starters in parallel allows for soft starting and soft stopping of motors without the need for large heat sinks during motor operation.

False

Shaded-pole motors produce high starting torque.

Increasing

Soft starting is achieved by ____ a motor's voltage gradually in accordance with the setting of the ramp-up control.

Compound

The DC ____ motor is used when high starting torque and constant speed are required.

Synchronous

____ speed is the theoretical speed of a motor based on the number of poles of the motor and line frequency.

Primary Resistor

____ starting is a motor starting method that uses resistors connected in the motor conductors to produce a voltage drop.

Reduced Voltage

____ starting is used to reduce the large current drawn from the power company when full-voltage starting is applied to large horsepower motors.

Centrifugal Switch

A(n) ____ opens to disconnect the starting winding when the rotor reaches a preset speed.

Induction

A(n) ____is a motor that has no physical electrical connection to the rotor because there are no brushes.

T1;T3

Although any two line can be interchanged to change the direction of rotation of a 3 phase motor, the industrial standard is to interchange ____ and ____.

False

An adjustable motor base complicates the installation of a motor and the tensioning of belts or chains.

True

Analog input devices/signals connected to electric motor drives include potentiometers and variable voltage inputs.

True

Angular misalignment is misalignment caused by two shafts that are not parallel.

PLC

Combining a(n) ____ and an electric motor drive allows for maximum control and monitoring of a motor.

False

DC motors require less maintenance than AC motors.

True

Direct hard wiring is the most straightforward and oldest motor control method.

True

Each National Electrical Manufacturers Association (NEMA) design class of motor has different starting torque values.

Voltage

The ____ applied to the stator of an AC motor must be decreased by the same amount as the frequency when controlling speed.

Duty Cycle

The ____ rating of a motor is determined by whether the motor delivers rated horsepower continuously or for short periods of time.

False

The field is the part of the armature that connects each armature coil to the brushes by using copper bars that are insulated from each other with pieces of mica.

True

When a dual voltage rated motor is used, the higher voltage is preferred.

series

When a dual-voltage, wye-connected, 3 phase motor is connected to high voltage, the individual coils of each phase will be in ____.

True

When connecting a dual-voltage motor, the higher voltage is usually preferred.

Parallel

When connecting a dual-voltage, delta-connected, 3 phase motor to low voltage, the individual coils of each phase are in ____

False

When electric motor drives are used to control motors, the type and level of the input supply voltage must match the rated type and voltage level of the motor.

Two

When motor starters are used to perform motor reversing, ____ contactors are required.

True

A capacitor motor is similar in design to a split-phase motor.

2

A capacitor start-run motor uses ____ capacitor(s) for successful operation.

500

DC series motors can develop ____ % of a full-load torque upon starting.

True

Electric motor drive manufacturers build drives to sizes that follow the standard horsepower rating of motors.

AC

Electric motor drives are either AC drives or DC drives, with ____ drives being the most common.

True

Electric motor drives are programmed to apply a voltage boost at low motor speed to compensate for the power loss of a motor.

True

DC drives control speed by varying the amount of voltage and current on the field and armature of the motor.

0.95

Typical service factors include all of the following except ____.

False

Typically, dual-voltage, 3 phase motors have 12 leads coming out of the motor box.

18

Typically, for every ____ F temperature rise above the NEMA rating, the usable service life of a motor is cut in half.

True

Typically, the control voltage used by electric motor drives is a low voltage, 24 VDC.

False

Typically, triacs are used a solid-state DC switches.

Local

When using the ____ method, motor sped is controlled from the keypad of the electric motor drive.

False

Wye-delta motors are specially wound with nine leads extending from the motor to enable the windings to be connected in either a wye or delta configuration.

Name Plate

____ information is used when taking electrical measurements to verify proper operation of a motor or to troubleshoot a problem.

Slip

____ is the difference between the synchronous sped and the actual speed of a motor.

Motor Efficiency

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

Parallel

____ misalignment is misalignment caused by two shafts that are parallel but not on the same axis.

Special Purpose

____ motors are used when motors are required to operate in abnormal service conditions such as high ambient temperature or extreme dampness.