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Definition
| A physical or chemical change of matter or conversion of energy. |
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Definition
| regulation or manipulation of the variables influencing a process to achieve a desired result |
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| What are some Common Control Schemes |
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Definition
| Feedback, feed forward, and cascade |
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| List the components of a control loop |
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Definition
| Primary element, Transmitter, Controller, Final Control element |
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Definition
| A specific device or group of devices that measure, monitor, and/or control a process |
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| Define: Measured Variable |
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Definition
| Process parameter monitored by the Primary Element |
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Definition
| The input variable that the controller recognizes as the desired control variable |
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| Define: Manipulated Variable |
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Definition
| Process parameter directly altered by the final control element |
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| Define: Controlled Variable |
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Definition
Process parameter over which a desired or influenced result is anticipated.
Output quantity of a system (level, temp, flow, etc.) |
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| State the purpose of the Primary Element |
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Definition
| Element of a control loop that detects and converts energy from the process into a value suitable for measurement |
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| State the purpose of the Measuring Element (Transmitter) |
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Definition
| Element of a control loop that interprets the measurement from the primary element and transmits a standradized signal to the controller |
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| State the purpose of the Controlling Element (Controller) |
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Definition
| Process control element that compares the actual value to the desired value (set-point) and applies preset algorithms to create a correction signal. |
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| State the purpose of the Final Control Element |
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Definition
| Process control element that directly changes the value of the manipulated variable |
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Definition
| A set of specific functions or instructions applied to a given varible |
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| Describe: Cyclic stability response |
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Definition
| decreasing oscillation of the wave until stability is reached. |
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| Describe Aperiodic stability responses |
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Definition
| Controlled variable returns to the stable condition in the shortest period of time with no overshoot |
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| Describe Over-dampened stability response |
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Definition
| controlled varibale returns to the stable condition with no overshoot but the recovery time is long |
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| Citeria for Quality Control:Mininum Area |
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Definition
| Minimum area under the response curve |
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| Criteria for Quality Control:Mininum Disturbance |
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Definition
| the control action should create the minimum disturbance to both the manipulated variable and the conrolled variable |
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| Criteria for Quality Control: Minimum Amplitude |
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Definition
| The amplityed of the deviation is minimized |
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Definition
| A characteristic of a process that enables the process to store energy |
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Term
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Definition
| A characteristic of a process that enables the process to store energy |
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Term
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Definition
| A Characteristic of a process that opposes the transfer of energy |
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Definition
| The period of time between when a controlled variable changes and the change is sensed |
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| 3 things to know about Two Capacity Processes |
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Definition
| Two or more capacity process react slower, have a greater chance of going into oscillations, and one change in the first capacity can cause a change in the second capacity |
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| How do you obtain the Time Constant of a system |
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Definition
| Mulitply the change in the controlled variable by 63.2% and determine the amount of time it took to reach that value from the reaction curve |
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Term
| Name one of the most common mistake a Technician can make when tuning a controller |
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Definition
| When tuning this process, the Technician thinks the controller is responding too slowly, when in reality the controller is responding too fast |
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Term
| 3 things to know about integral |
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Definition
1. Integral provides a linear ramping output to a sustained step change input
2.The slope of the ramp is determined by the magnitude of the propoertioal output step change
3. If integral is 2 Repeats/Min (.4min/Rep), the ouput will repeat the output step change (caused by the proportional component) in 30 seconds |
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| 3 things to know about Proportional band |
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Definition
1.An advantage of proportional action is that it provides immediate output action to a change in input
2.With a proportional band of 100%, it takes 100% of the input range to create a 100% change in output
3.As the Proportional Band is narrowed it requires less input changes to create 100% change in output. |
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| What happens to the offset when the PB is narrowed |
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Definition
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| What happens to the offset when the PB is widened |
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Definition
| Offset error is increased |
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| 3 Things to know about Derivative |
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Definition
1.Derivative action responds to the rate of change of the error signal
2.The initial overshoot is reduced with derivative and the process stabilizes sooner
3.Rate time is the time difference to reach the same output with the same disturbance between a P+D controller and a proportional only controller |
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Term
| What will too long of a dirivative action in a proportional plus rate controller lead to |
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Definition
| Too long a derivative time will over-dampen controller output (Increases time for the process to return to setpoint |
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Term
| Without the bellows a device that uses one in a balance beam set up would have _________ |
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Definition
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| Mechanical advantage of a lever = |
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Definition
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| Mechanical advantage of an inclined plane = |
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Definition
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Term
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Definition
| A device used to convert a pressure into force or movement |
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| Describe the purpose of the Restriction |
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Definition
| Converts flow to differential pressure or differetial pressure to flow |
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Term
| Descibe the purpose of the Booster Relay |
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Definition
| High-Volume oitput pressure for rapid stroking when signal changes exceed the dead band limit |
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| Where do you adjust the dead band on a booster relay |
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Definition
| Bypass restriction adjusting screw |
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Term
| In logic drawings what does TDPU stand for? What does it do when an input is present? What does it do when an input is removed? |
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Definition
TDPU stands for Time Delay Pick Up
When an input is present, the output will be present after a time delay
When an input is removed, the output is removed instantaeously |
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Term
| In logic drawings, what does TDDO stand for? What does the output do when an input is present? What does the output do when an input is removed? |
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Definition
TDDO stand for Time Delay Drop Out
When an input is present, the output will be present
When the input is removed, the ouput will be removed after a time delay |
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Term
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Definition
| error corection following a disturbance |
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Term
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Definition
| control of disturbances, which could cause a process error |
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