Questions and Answers
The variable which is adjusted manually or by means of control mechanism is called_______.
Manipulated variable
Identify this symbol.
Pneumatic signal line
In flow control loop, the range of the flow rate is given as 0 LPH to 100 LPH. The 75 LPH flow rate corresponds to ________ of current.
7.5 mA
In 4-20 mA current signal, 4 mA current represents_____________ value.
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The basic function of an electronic transmitter is to
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Which of the following accessory can be used in the installation of DPT for flow rate measurement?
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In level measurement, zero elevation is necessary when
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Manifold is __________
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In liquid pressure control loop, _______________ control action is recommended.
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In on-off control mode, to avoid cycling behavior of the controller _________ is purposely provided.
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Suppose a process error lies within the neutral zone with P= 25%. At t=0, the error falls below the neutral zone. If K= 2% per second, find the time when the output saturates.
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If the critical gain is 26, what is the proportional gain of a single-mode controller?
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In quarter amplitude decay ratio, if the magnitude of the first overshoot is 16, what is the magnitude of the second overshoot?
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Setting the optimum values of proportional gain, integral time, and derivative gain in a PID controller to improve its performance is called _______________ of the controller.
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A 9% change in the controlling variable causes a 3.9% change in the controlled variable in 4.8 minutes. Determine the process reaction rate.
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Identify the experimental step to implement the Z-N open loop method of controller tuning.
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In a power plant, pressure control loop no. 071 uses a current to pressure converter as one of the components, the actuator used in this loop is __________.
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Which characteristic gives good control and high rangeability?
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Which of the following is part of the trim in a control valve?
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Which valve is a rotary type of control valve?
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The U.S. number of gallons of water that passes through a fully open valve in one minute with a pressure drop of 1 psi across it at 60°F is called_________.
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Which of the following components improve the performance of a control valve?
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Which of the following is a pressure-reducing device?
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Study Notes
Process Control Loop Components
- The variable that is adjusted manually or by means of a control mechanism is called the manipulated variable.
- Set point value is the desired value of the controlled variable.
Signal Lines
- The symbol for pneumatic signal line.
Flow Control Loop
- In a flow control loop, a flow rate of 75 LPH corresponds to a 75% current signal.
4-20 mA Current Signal
- In a 4-20 mA current signal, 4 mA represents 0% value and 20 mA represents 100% value.
Electronic Transmitter
- The basic function of an electronic transmitter is to respond to a measurand and convert it into a 4-20mA signal.
Installation of DPT
- An impulse line, manifold valve, and orifice plate can be used as accessories in the installation of a DPT for flow rate measurement.
Level Measurement
- Zero elevation is necessary when the pressure on both sides of the transmitter are equal.
Manifold
- A manifold is a type of valve.
Control Actions
- Proportional-integral control action is recommended for liquid pressure control loops.
- In on-off control mode, a dead time is purposely provided to avoid cycling behavior of the controller.
Controller Tuning
- The tuning of a controller involves setting the optimum values of proportional gain, integral time, and derivative gain to improve its performance.
Quarter Amplitude Decay Ratio
- In a quarter amplitude decay ratio, the magnitude of the first overshoot is four times the magnitude of the second overshoot.
Process Reaction Rate
- The process reaction rate can be calculated from the percentage change in the controlling variable and the corresponding change in the controlled variable.
Z-N Open Loop Method
- The experimental step to implement the Z-N open loop method of controller tuning involves discontinuing the controller output from the final control element.
Actuator
- A pneumatic type actuator is used in pressure control loop no. 071.
Control Valve Characteristics
- Equal percentage characteristics give good control and high rangeability.
Control Valve Components
- The closure member is part of the trim in a control valve.
Valve Types
- A butterfly valve is a type of rotary control valve.
Control Valve Coefficient
- The control valve coefficient is the U.S. number of gallons of water that passes through a fully open valve in one minute with a pressure drop of 1 psi across it at 60° F.
Control Valve Performance
- A positioner improves the performance of a control valve.
