Chapter 17 Flashcards
THe automatic operation preformed by an industrial manufacturing machine is referred to as
Process control
Timing functions used to control an operation by industrial manufacturing machines preformed by \_\_\_\_\_\_\_ Ladder logic Sequential drum controller Programmable controller Computers All above
Al above
Which of following industrial operations is referred to as a process
Fluid rate through a pipe
Ingredients filling a vat to a level
Heat applied to a vessel for chem reactions
Vacuum pressure applied to a confined tanks
All above
R
All above
T/F
The output signal of a sensor is referred to as the controlled variable
False the output is the measured variable
List 3 influences that cause a controlled variable to change
A disturbance appears
Load demands vary
Setpoint are adjusted
Dynamic response pertains to Dead time Reaction time Inertia All above
All above??????
T/F
Dead time is influences by the mass of the material from which the controlled variable is made
F??
T/F the pure lag of a controlled variable is determined by the quantity and the type of material from which it is made
True
One time constant is defined as ____percent of the controlled variable’s change after it is exposed to an energy change
63
The dynamic response of a control loop can be improved by ___
Selecting a controller with proper operation
properly tuning a controller
Both
Both
TF
The amount at which the final control element turns on in an ON OFF system is proportional to the error signal
False
What are 2 household applications that purposely have a deadband to turn a device on and off
Home heating thermostat
Liquid water tank? Steam boiler
T/F
The output of the proportional controller moves the final control element to a definite position for each value of the controlled variable
True
The avg voltage of a time proportioning controller changes by 5 percent, the ___ will change by___ percent
F
Page 373
The proportional ___Setting affects how rapidly the controlled variable changes in response to a step change or load change
Gain
Band
A nd b
Gain
A controller with a proportional band of 50 will produce a proportional gain of ____
2
When the controlled variable is above the proportional band the proportional action will cause the final control element to be ___
On
Off
Partly on
OFF
A controller has more sensitivity if ‘tis proportional band is ___
Narrower
Wider
Narrower
What. Condition might occur if a controller is too sensitive
Sluggish response
Excessive cycling
No signal change
Cycling
Controller with what kind of control mode elimates offset automatically
Integral?
TF tIf the reset rate adjustment on a controller is increaSed the intergal time will____
Increase
Decrease
Stay same
Decrease
A reset rate of 10 repeats per minute equals an integral time of ___minutes per reapet
R
6 seconds
What kind of controller action is related to the rate at which an error develops
Derivative
While tT/F
The derivative mode is recommended in applications where the controlled variable lags behind the change of the final control element
False
When tuning a cascade control system with 2 loops, which loop should be tuned first
Primary
Secondary
Secondary
Which of the following terms describes a control strategy in which the output of one controller is used to maninpulate the setpoint of another controller Ratio Cascade Feed forward Adapative
Cascade
The ___ controller in a cascade system revceives the signal that represents the condition of the controleld variable
Prime
Sec
Primary
IN a cascade system, the _____ loop is consider the primary loop
Inner
Outer
Outer
Which of the following statements are true about feed forward control (more than one answer possible)
Should be used with feedback control
Can compensate for unmeasurable disturbs
Outsputs casues manipulated variable to change
Improves speed at which corrections are made
Should be used with feedback control and
Page 388?
Which of the following is true
Feedforawrd control is based on observing changes in the controlled variable and then adjusting he manipulated variable to compensate
Feed forward control helps to prevent changes in the controlled variable before they occurs
FBoth true
T/F
When 2 or more ingredients are blended in a mixer the flow of each one is controlled by a ratio control system
True
A strategy in which the flow rate of one fluid stream is maintained at some proportion to the flow rate of another fluid stream is Cascade Feedback Ration control Adapative
Ratio control
T/F
Wild flow ingredient in ration control is measured
True
In ratio control the reference flow rate is referred to as ___ flow
Wild
An adaptive controller sues a combo of software programming and microelectronics to compensate for ___easurements
Linear
Non linear
Non linear
Which of the following process measurements produce a non linear signal…more than one
Differential pressure flowmeter
Ultrasonic level meter
PH of a. Solution
None of absolve
Differential pressure
PH of solution
