CME 405 QUIZ 2 QUESTIONS AND CORRECT DETAILED
ANSWERS (VERIFIED ANSWERS) ALREADY GRADED A+
controller Ans✓✓✓a special-purpose calculator based on the error
signal that indicates the necessary changes in the manipulated variable
(MV)
electronic, pneumatic, mechanical, and hydraulic
Ans✓✓✓classifications of controllers (4)
input elements, comparator, calculator, & output element
Ans✓✓✓controller elements (4)
two-position control Ans✓✓✓a type of control action where the
controller output (OP) is quickly changed to either maximum (on) or
minimum (off) value depending on whether the controlled variable (PV)
is greater or less than the set point (SP)
dead zone, differential gap Ans✓✓✓In the most commercial two-
position controllers, there is a ___ ___
of about 0.5 to 2 % of full range. It is also called ___ ___
three position control Ans✓✓✓A variant of two-position control with
differential gap is ____ ____ ____, wherein the controller responds with
an intermediate output (e.g., 50%) when controlled variable (PV)
changes within the values indicated by the dead zone.
,Proportional action (P), Integral action (I), Derivative action (D)
Ans✓✓✓three position controller 3 modes:
proportional control mode Ans✓✓✓The most basic continuous control
mode where the controller output (OP) is proportional to the error input
signal to the controller; characterized by controller gain; simplest
continuous control mode, can damp out oscillations
To keep the process variable (PV) within an acceptable range around a
required setpoint (SP). Ans✓✓✓why is proportional control necessary?
controller output (CO) while on "manual" (before controller is switched
to automatic) - MO (also ''b") is called bias Ans✓✓✓What is MO?
bias Ans✓✓✓controller output when error is zero
to maintain the process variable at the set point value with the present
load on the system Ans✓✓✓function of MO
kp = proportional mode gain constant and kc = controller gain
Ans✓✓✓kp and kc
offset (residual error) Ans✓✓✓deviation of the controlled variable from
the setpoint expressed in process units
, integral control action; also known as reset Ans✓✓✓A control action
which moves the controller output according to the integrated error over
time
• To compensate for the fact that an error has existed for a period of time
• To remove any error that may exist (offset), which may have been left
by proportional control alone Ans✓✓✓why is integral control action
needed?
reduces the stability of the control loop Ans✓✓✓disadvantage of
integrated control action
integral time Ti Ans✓✓✓the amount of time it takes the controller
output to change by an amount equal to the error
-Proportional control:
A continuous control mode where the controller output is proportional to
the error input signal to the controller
-Integral control:
A control action which moves the controller output according to the
integrated error over time. Ans✓✓✓proportional control vs integral
control:
proportional plus integral (PI) controller Ans✓✓✓A ____ ____ ____
____ will give a response period that is longer than a P-only controller,
but much shorter than an I-only controller
ANSWERS (VERIFIED ANSWERS) ALREADY GRADED A+
controller Ans✓✓✓a special-purpose calculator based on the error
signal that indicates the necessary changes in the manipulated variable
(MV)
electronic, pneumatic, mechanical, and hydraulic
Ans✓✓✓classifications of controllers (4)
input elements, comparator, calculator, & output element
Ans✓✓✓controller elements (4)
two-position control Ans✓✓✓a type of control action where the
controller output (OP) is quickly changed to either maximum (on) or
minimum (off) value depending on whether the controlled variable (PV)
is greater or less than the set point (SP)
dead zone, differential gap Ans✓✓✓In the most commercial two-
position controllers, there is a ___ ___
of about 0.5 to 2 % of full range. It is also called ___ ___
three position control Ans✓✓✓A variant of two-position control with
differential gap is ____ ____ ____, wherein the controller responds with
an intermediate output (e.g., 50%) when controlled variable (PV)
changes within the values indicated by the dead zone.
,Proportional action (P), Integral action (I), Derivative action (D)
Ans✓✓✓three position controller 3 modes:
proportional control mode Ans✓✓✓The most basic continuous control
mode where the controller output (OP) is proportional to the error input
signal to the controller; characterized by controller gain; simplest
continuous control mode, can damp out oscillations
To keep the process variable (PV) within an acceptable range around a
required setpoint (SP). Ans✓✓✓why is proportional control necessary?
controller output (CO) while on "manual" (before controller is switched
to automatic) - MO (also ''b") is called bias Ans✓✓✓What is MO?
bias Ans✓✓✓controller output when error is zero
to maintain the process variable at the set point value with the present
load on the system Ans✓✓✓function of MO
kp = proportional mode gain constant and kc = controller gain
Ans✓✓✓kp and kc
offset (residual error) Ans✓✓✓deviation of the controlled variable from
the setpoint expressed in process units
, integral control action; also known as reset Ans✓✓✓A control action
which moves the controller output according to the integrated error over
time
• To compensate for the fact that an error has existed for a period of time
• To remove any error that may exist (offset), which may have been left
by proportional control alone Ans✓✓✓why is integral control action
needed?
reduces the stability of the control loop Ans✓✓✓disadvantage of
integrated control action
integral time Ti Ans✓✓✓the amount of time it takes the controller
output to change by an amount equal to the error
-Proportional control:
A continuous control mode where the controller output is proportional to
the error input signal to the controller
-Integral control:
A control action which moves the controller output according to the
integrated error over time. Ans✓✓✓proportional control vs integral
control:
proportional plus integral (PI) controller Ans✓✓✓A ____ ____ ____
____ will give a response period that is longer than a P-only controller,
but much shorter than an I-only controller
