Test 2 Flashcards

1
Q

Controller Tuning

A

The process of determining the tuning coefficients for the PID controller to obtain a desired controller response to process disturbances.

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2
Q

Decay Ratio

A

Measure of how quickly an overshoot decays from one oscillation to the next as the controller brings the process to the setpoints.

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3
Q

Overshoot

A

The change of a PV that exceeds the upper deadband value when there is a disturbance to a system.

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4
Q

Deadtime

A

change is made to first sensed.

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5
Q

Rise time

A

The length of time required for a PV to cross the ultimate value after a step input change, such as a setpoint change.

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6
Q

Dynamic response time

A

The length of time required for a PV to remain within 5% of its ultimate value following a step input change.

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7
Q

Gain Margin

A

The factor by which controller gain may be increased before instability occurs, and therefore is a measure of relative stability.

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8
Q

Self-tuning controller

A

Controller that has built-in algorithms or pattern recognition techniques that periodically test the process and make changes to the controller tuning settings while the process is operating.

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9
Q

Stand-alone controller

A

Controller that has its power supplies, input signal processing, controller functions, output signals, and displays contained in the same case.

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10
Q

Pretuning checks

A
  1. Ensure that the controller action is selected correctly. (direct or reverse)
  2. Determine which controller functions are needed for the process. (Integral, Derivative, or Proportional)
  3. Determine the initial tuning values that are to be used for the chosen controller functions. (Initial values)
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11
Q

Setpoint step change method

A

Manual tuning method that consists of making small changes in the setpoint and observing the responses.

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12
Q

Setpoint step change method steps

A
  1. Controller must be in auto mode and the measurement should be steady.
  2. Adjust proportional gain, integral time, and derivative function accordingly.
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13
Q

Tuning map method

A

Procedure for controller tuning that compares process curves to one of numerous typical closed loop response curves.

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14
Q

Ziegler-Nichols Tuning Method

A

Variation of one quarter wave decay.

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15
Q

Ziegler-Nichols closed loop tuning

A

Tuning a controller by increasing the gain until the system cycles at the point of instability.

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16
Q

Ziegler-Nichols open loop tuning

A

Tuning a controller based on open loop response to a step input.

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17
Q

Ultimate Gain (Ku)

A

the closed loop proportional gain at the point of oscillation.

18
Q

Ultimate Period (Tu)

A

the closed loop cycle time at the point of oscillation.

19
Q

Digital Controller

A

Controller that uses microprocessor technology and special programming to perform the controller functions. (Digital version of an electrical processor)

20
Q

Stand-alone digital controller

A

Controller with all required operating components enclosed in one housing.

21
Q

Configuration

A

Selection of programmed software packages embedded in a controller representing available features that can be chosen.

22
Q

Direct computer control system

A

Control system that uses a computer as the controller.

23
Q

Distributed control system (DCS)

A

Control system where the individual functions that make up a control system are distributed among a number of physical pieces of equipment that are connected by a high-speed digital communication network.

24
Q

Scan speed

A

The time it takes to access all the I/O points and go through the configuration program.

25
Q

Programmable Logic Controller (PLC)

A

Control system with an architecture very similar to that of a DCS, with self-contained power supplies, distributed inputs and outputs, and a controller module, all connected on high-speed digital communication networks.

26
Q

Null-balance controller

A

Electric controller that generates an output signal to a final control element based on a measurement from a process. (thermal couple)

27
Q

Analog output controller

A

Electric controller that has 4 mA to 20mA DC electric current as the output.

28
Q

Operator Interface

A

The means by which an operator can observe and control a process.

29
Q

Stand-alone display system

A

A display system designed for use with smaller digital control systems and has the electronics and display packaged together in a panel mounted enclosure.

30
Q

PC-based display system

A

Display system that uses standard personal computer hardware and special software to display full graphics, control functions, alarms, trends, etc.

31
Q

2 types of Electric Controllers

A
  1. Null balance

2. Analog Output

32
Q

Digital Recorder

A

Device that uses local memory to record process data.

33
Q

Configuration format

A

One of the various programming methods that have been developed to provide a simplified method for instructing various digital control systems on how to control a process.

34
Q

Pick and Choose

A

Configuration format where the configuration is selected for a list of available functions.

35
Q

Function block configuration

A

Configuration method that uses a library of functions provided by the manufacturer.

36
Q

Function block

A

stand-alone procedure designed to perform a specific task and can be linked with other function blocks to form complex control strategies.

37
Q

Ladder Logic

A

Configuration method that consists of two vertical rails, with sequential logic placed between them.

38
Q

Structured Text

A

Type of configuration that based on structured programming languages.

39
Q

Sequential function chart

A

Type of configuration format consisting of a series of condition statements, parallel paths, and action blocks, which begins with start command and ends with existing scan.

40
Q

Tuning Performance Standards

A
  1. Decay Ratio
  2. Ovsershoot
  3. Deadtime
  4. Rise time
  5. Dynamic response time
  6. Gain Margin
41
Q

Tuning Methods

A
  1. Self Tuning

2. Stand-alone Controller

42
Q

Configuration Formats

A
  1. Pick and Choose
  2. Function block configuration
  3. Ladder logic
  4. Structured Text