Chapter 1 TEST Flashcards by Richard van Horne

List two examples of controlled variables for motion control applications and two examples from process control applications.

speed Position

Temperature and pressure

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An open loop system does not have a

feedback loop

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T or F

The basic concept of feedback control is that an error must exist before some corrective action can be made.

True

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A pressurized tank must maintain a gas at 325 PSI. A pressure sensor is used to measure the condition of the controlled variable. As the gas cools, the pressure in the tank decreases. When it drops to 300 PSI, a valve is opened, which allows steam to flow to a heat exchanger inside the tank. The additional steam heats the gas and causes pressure to rise.

What is the controlled variable in this process?
Gas pressure
What is the manipulated variable in this process?
Steam flow
What is the setpoint?
325 PSI
What is the measured variable
pressure

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Altering the________ variable causes the condition of the ______variable to change

manipulated

controlled

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The manipulated variable and controlled variable are synonymous terms in a closed-loop system

FALSE

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List another name for each of the following terms.

Motion control

Process control

Batch proces

Servo

Instrumentation / temperature

Sequential Process

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The output of the measurement device is called the

Feedback signal

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Feed-forward control is seldom used except in combination with feedback control.

True

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The control method used in ?servo/process? control applications is to sustain a constant condition of the controlled variable.

process

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A DC series motor has____

highest

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A cumulative compound motor has__ than a differential compound

higher starting torque

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Torque is produced by a motor when the load it is driving

does not move
moves
both

both

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In a DC motor, an increasing mechanical load

Increases Armature current

has no effect on armature current
Decreases Armature current

Increases Armature current

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Work is performed by a motor when the load it is driving ___________ moved a distance.
is not
Is
either answer

fis

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When connecting a compound motor for operation, which leads are wired in parallel with the power supply?

A1 - A2
C1 - C2
F1 - F2
S1 - S2

F1 - F2

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Which of the following are functions of the brushes and commutator? _________

(choose all that apply)

to provide a path for field current flow

to provide a path for armature current flow
to connect and disconnect armature coils in sequence

t provide a path for armature current flow

to connect and disconnect armature coils in sequence

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Refer to figure 5-14. work = distance x force

How much work in ft-lb is accomplished when a motor exerts a torque to lift a 473 pound load a distance of 28 feet. Do not include the unit designation ft-lb: example 3250

fr13244.0

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Motor efficiency. Percent:efficiency=\frac{power:out}{power:in:}x:100 and power out = hp x 0.746kW

The power consumed by a motor is 10.652 kW , the motor produces 12 hp of output power. Round your answer to 2 decimal places and do not include the symbol %: example 94.52

t84.04

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The RPM that the rotating field moves around the Stater is called ____________ (two words )

synchronous speed

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In a synchronous motor, the DC excitation is applied to the stator or rotors magnetic field.

rotor’s

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To change the rotation of a split-phase AC motor,_______.

reverse the main and auxiliary windings with respect to each other

reverse the power leads

both answers

reverse the main and auxiliary windings with respect to each other

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Which components of a DC motor are not found in an AC motor?
	fan assembly
	Armature
	brushes and commutator
	field windings

brushes and commutator

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In a resistance start motor, current in the auxiliary winding always LEADS OR LAGS the current in the main winding.

Leads

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Once the split-phase motor reaches [A] percent of its synchronous speed, the centrifugal switch [B] to [C] the________ windings.

75 to 80 opens Disconnect Auxiliary

The capacitor-start capacitor-run motor has how many capacitors?

In a synchronous motor, stator current will lead the applied voltage if the DC motor field is over excited or under excited

overexcited

In actual practice, the _____ leads are interchanged to reverse the direction of a universal motor.

Armature

Micro stepping is achieved by__________

both answers

The maximum number of steps a stepper motor can make in a second is called ___________

stepping rate

The difference between the two classifications of PM motors is whether the rotor and field are made of permanent magnets or coils. T F

True

In a variable reluctance motor, if the salient poles are 15° apart and the rotor poles are 20° apart, the step angle is ____ degrees.

In an AC Servo motor, the phase-shifted voltage is supplied to the ____ winding.

auxiliary

The stepper motor is typically used in a(n) ____ -loop system.

open

The speed of an AC Servo motor is changed by varying the voltage applied to ______

the auxiliary windings

The amount of force required to move the rotor of the BDCM away from the held position is called

holding torque

The speed of a wound armature PM motor is varied by changing the current applied to the

armature

The speed at which a stepper motor turns is increased by ______ applied to the stator.

Increasing the stepper rate

Find the cross product of vectors U and V such that U x V U=0i+0j+1k V= 0i+1j+0k

-1 0 0

The speed at which a stepper motor turns is increased by ______ applied to the stator.

Increasing the voltage

The Capacitor/resitance – start motor has the largest starting torque.

Capacitor

The difference between the setpoint in the feedback signal is referred to as the _______ signal, and is produced by the _________ detector.

error error

Which of the following influences causes a controlled variable to change? the setpoint is adjusted a load demand varies A disturbance occurs all three answers

all three answers

The controller can be considered the brain of a closed-loop system.

True

The _______ is sent to the final control element

control signal

The objective of _____ control is to prevent the controlled variable deviating from the setpoint.

feed-forward

The device that provides the muscle to perform the work in the closed loop system is referred to as the

actuator

When the load on a DC shunt motor is increased, its speed will________ and the amount of torque developed will _________

decrease, increase

Armature reaction is corrected by _________ , which is/are used to shift the neutral plane back to the proper position.

interpoles

The interpoles are always connected in parallel with the armature

False

When the motor speed increases, the CEMF in the Armature increa/decreas

increase

How much power is needed when a torque is applied to a 413 lb mass that is moving 33 ft for 2 minutes. Do not include the unit designation ft-lb/min: example 3250

6815.0

AC motors that run at the same speed as the rotating magnetic field are called__________ motors.

synchronous

During operation, if the resistance of a wound – rotor motor is set to zero, it performs very much differently than a squirrel cage motor.

False

A(n) ____ in the external resistance of a wound – rotor motor causes an increase in the rotor resistance and therefore a reduction in the rotor current and speed.

increase

A Duty Rating of 20 on the nameplate of a motor indicates that it is designated to run continuously for 24 hours a day.

False

The A(amps) value on the nameplate for a three – phase motor indicates how much current will draw. each phase the entire motor

each phase

Calculate the percent slip of an induction motor that has a synchronous speed of 3600 RPM and a motors speed of 3330 RPM. Compute your answer to 2 decimal places and do not include the % symbol: example 4.03

actual-synch //// synch 7.5

The CAP/RES – start motor is well suited for applications that require frequent starting loads, such as a refrigerator.

Capacitor

In a synchronous motor, stator current will lead the applied voltage if the DC motor field is

overexcited

Find the cross product of vectors U and V such that U x V U=-2i+3j+4k V= 3i+7j+2k

-22 4 4

A differential compound motor has __________ then a cumulative compound motor.

better constant speed

Which of the following conditions is compensated for by using the forward-control? Excessive lag time feedback signal large disturbances an error signal

Excessive lag time large disturbances

List one example of a measurement device for motion control application and one example for process control application motion control process contro

Tachometer thermometer

List two favorable features of synchronous motors.

power factor correction constant speed

The speed of an AC motor depends on the of the power supply and the

frequency | number of poles

What is the RPM speed of a single-phase 10-pole AC motor operating from a 60 Hz power source?

720.0

The speed of a universal motor can be controlled by________. Tapping a field coil at various points Either answer Using a variable resistor

Either answer

The direction of the torque in a shaded – pole motor is towards the

Shaded pole

The amortisseur windings of a synchronous motor perform a similar function to the bars and shorting rings of a squirrel cage induction motor.

TRUE

If the stator's magnetic field of the VR stepper motor moves clockwise, the rotor turns

counterclockwise

A stepper motor with twice the step angle of a second stepper motor will turn at _____ the RPM if the stepper rate applied to both is the same.

TWICE

The measured variable represents the condition of the controlled variable. t f

True

To change the direction of the DC shunt motor with compensating windings, you must interchange leads ___ or ____.

F1 and F2 A1 and A2

In a DC series motor, if the Armature current is reduced to one half of its full load rating, the torque is ________

reduced

A(n) ___ field must be established in a split-phase motor to produce the starting torque.

rotating

When feedback and feedforward control are performed together, the primary function of the feedforward is to make corrections for ____disturbances, and feedback control is to make corrections for ________ disturbances.

measurable unmeasurable

A DC shunt motor operating at 240 V draws 4.5 A. It has an output of 1 hp. Its efficiency is_____ %.