Chapter 8-12 Flashcards
How close a measurement corresponds to it’s true value
Accuracy
Pre-CERT mathematical functions calculated in a controller can be mechanical analog or digital the three most common output functions deal with proportionals, integral, derivative,tuning.
Algorithms
Sensing, measuring, comparing, calculating, correcting, and manipulating
Basic control functions
When a control has feedback, controller in automatic mode
Closed control loop
A component of a controller that compares the measurement to a predetermined set point
Comparator
The control loop component that receives the appropriate signal from the transmitter and compares the signal to a desired value ,set point, if there is a difference, then the output of the comparison causes the calculation to be performed to cause a corrective response by the controller good signal to the final control element
Comparing, calculating and correcting, element
A process variable that is so used to initiate the control signal
Controlled variable
And instrument the receives the signal from the transmitter and compares it to a certain point, and produces an output to a final control element
Controller
The control loop component that converts the soonest process very rude and transmits the measured signal
Converting and transmitting element
A device that receives information in 1 pound of an instrument signal and changes it Into another form of an instrument
Converting device
The accuracy of the instrument (+/-) full scale
Device error
Characterized by do you doing that is represented as coated information in the form of binary numbers, used to transmit data to and from field transmitters on a twisted pair of wires may also be between computers and computer components
Digital signal
Either an Analog or digital signal, current or voltage signal
Electronic signal
The most common type of control loop where the change caused by the output of the controller is fed back to the process providing a self – regulating action
Feed back loop
The last active device in an instrument control loop, directly controls the manipulated variable, usually they control valve, louver, or an electric motor
Final contro element
A standard bias has been added to the instruments signal (Pneumatic 3-15 psig or electronic 4–20 MA , Instead of reading zero the reading is 3 psig or4mA
Live zero
The accumulated over each device in the loop, calculated as the square root of the sum of the sum of the squares of individual device accuracy
Loop error
The final control element, control valve is manipulated by the corrective response of the controller output so that the process variable is maintained the appropriate set point value
Manipulating element
A process variable that is measured
Measured Variable
A way of mechanically transmitting the motion will be primary sensor to a controlling mechanism, Conveys linear or rotary motion but using a pivoting crank
Mechanical link
When I control he does not have feedback, controller in manual mode
Open control loop
One wire per bit or 64+ wires for a 64 – Bit binary word, used primarily in short distances, a few feet
Parallel data communication
An instrument communication with the range Of 3- 15 psig must have an air supply, has a lag time associated with the signal, relatively short transmission distances
Pneumatic signal
How close repeated measurements or versus the action, reproducibility , The closing is over repeated measurements of the same quantity on the agreement between the numerical values to reman measurements made in the same way and expressed in terms of deviation
Precision
The act of regulating One or more process variables so that a product of a desired quality can be produced
Process control
The difference between set point in process Variable
Process error
The act of detecting
Sensing
The control loop component that detects, or senses, the process.
Sensing element
To data wires, the most common means of communication used between plant equipment
Serial data communication
The desired process value
Set point
A device that transmits a signal from one device to another
Transmitter
Asensing element that can stand alone or is individually distinct, connected to the transmitter by sensor wires
Discrete sensing element
A tube that is usually made of stainless steel and allows the prices vary want to be sentenced by the sensor located in the transmitter
Impulse tubing
A range of ordered mornings that indicate the numerical values of the prices variable
Instrument scale
Where the sensing element is a physical part of the transmitter
Intergrally mounted sensing element
Evening in relationship between two scales, input versus output
Linear scaling
The number at the bottom of the scale
Lower range value, LRV
One number that is difference between the upper and lower range values on scale
Operating range
The act of equal eating the numerical value of one scale to it’s mathematically proportional value on another scale
Scaling
Detects the process variable, can be an integral part of a transmitter
Sensor
Part of a transmitter that effectively converts the process variable into a standard instrument signal, a device that converts one energy form into another
Signal converter transducer
The algebraic difference between the URV minus the LRV of a scale , Expressed as one number
Span
The language that instruments used to communicate between one another
Standard signal
The number at the top of the scale
Upper range value (URV)
A switch that allows a process technician to select either automatic or manual control from the front of a controller
Auto/manual switch
When the controller from automatic to manual or vice versa by adjusting the set point of the controller to the actual controlled point and then switching the mode, or switching from automatic to manual by simply repositioning in the mode selector
Automatic to manual and manual to automatic switching
A process upset occurs when a controller is switched from auto to manual mode
Bump
The act of changing the controller for manual to automatic or vice versa without a significant change in the controller out put
Bumpless transfer
Where the control loop is characterized by the output of One controller becoming the set point of another
Cascade control loop
The controller action or the control algorithm response such as PID or a program function
Control mode
Most common final control element in the processing industry has any actuating device to it drives the flow controling mechanism the plug or disk in a valve
Control valve
A controller response that is proportional to the rate at which the controlled variable deviates from the set point
Derivative action
The condition of the valve seat upon loss of instrument air or power failure
Fall-last(fail-in-place)
Change in output put divided by the change in input
Gain
The controller I would put response that is proportional to the length of time the controlled variable has been away from the setpoint
Integral action (reset)
When the controller is physically mounted in the processing area near the other instruments in the loop
Loval controller
Device is used to control air flow
Louvers (dampers)
Perceives the secondary loop as a separate entity; Response to one process variable and secondary controller response to another
Primary controller
The amount of deviation of the controlled variable from the set point required to use it to move the output of the controller through its entire range expressed as a percent of span
Proportional band(proportional gain)
The faster the rate of change in the process variable the greater the out put response
Rate action
Controllers that are designed to ratio(or proportion) Flow rate between to Separate flows Entering a mixing poinr, designed so that is output represents the exact flow rate needed by the controlled flow loop to remain in alignment with the desired ratio to be uncontrol led flow; may also be capable of receiving two separate flow inputs and rationing it output to the control valve located in the controller line
Ratio controller
Any controller that is not located in the processing area with the transmitter in control valve
Remote controller
A Set point received from an external source
Remote set point (RSP)
A special type of controller sometimes called a cascade controller or remote set point control, a standard controller with the capability of choosing to receive a remote set point from an external source or local, internal set point
Secondary controller
The mechanism By which a technician could manipulate the setpoint
Set point knob
Where are the output signal is divided between two final control elements
Split-range controller
Adjusting the control Action so that they produce an appropriate dynamic response to the process resulting in good control
Tuning
Flow in the process line where there is no control valve
Uncontrolled flow
Controller response to an increasing input with an increasing output
Direct
Controller response to an increasing input with a decreasing output
Reverse
Controller takes the full range of input to drive the output
Proportional
Control response to reset the measurement back to the set point
Integral
Controller response to the rate at which the variable changes
Derivative
A device that provides motion to a valve controlling purposes
Actuator
A device used to regulate and or control the pressure of a process fluid upstream of the device location
Back-pressure regulator
The housing component of a valve
Body
The top portion of the valve that connects the valve to the actuator, it can be removed to allow entry in the valve body cavity, usually contains the packing box and stem Mechanism
Bonnet
The only movable component in the valve that is actuated to open and close the flow path through the valve
Disc or plug
I’m actuator accessory used to manually override the actuator or to limit its motion
Handwheel
A device that converts a milliampere signal into a pneumatic pressure
I/P transducer (current to pneumatic transducer
A device used to regulate and or control the pressure of a process fluid downstream of the device location
Pressure reducing regulator
A self contained and self actuating controlling device used to regularly variables such as pressure, flow, level, and temperature in a process
Regulator
The stationary part of the valve trim connected to the body that comes in contact with the valve plug, when the bell plug is fully seated, the flow through the valve ceases
Seat
The device that provides the energy to move a valve in the opposite direction of the diaphragm loading motion so that the valve can be opened and closed proportionately with the instruments signal, also provides energy to return the valve back to it still safe condition
Spring
The pushing rodthe transfers the motion of the actuator to the valve plug
Stem
A device used to make the valve position match the controller output signal by positioning the moving parts of a valve in accordance to a predetermined relationship with the instrument signal received from the blue controller, may also be used to adjust the position of the valve according to the specifics needs or change the amount of signal needed to fully stroke the valve as a split range application
Valve positioner
The basic instrumentation symbol
Ballon
Common equipment such as pumps, towers, furnaces, Etc. are basic pieces of equipment for most processing facilities and have commonly recognizable, or basic equipment symbols
Basic equipment symbols
A flow scheme in a simple sequential blocked form
Block flow diagram (BFD)
A global, nonprofit technical society that develops standards for automation, instrumentation, control, and measurement
International society of automation (ISA)
Explanation of what the symbols and codes on a drawing represent, usually located on an individual drawing in a framed area or on a page within a set of drawings
Legend
Connectors between the basic pieces of equipment without which process streams could not be moved
Line symbols
Contains more detail than a PFD to include piping and instrumentation details and the entire control system
Piping and instrumentation diagram (P&ID
A pictoral description of an actual process including the major processes equipment while provinding process information including the heat and material balances, usually develop when initiating the design of a new plant
Process flow diagram (PFD)
Various graphical representation’s used to identify equipment, lines, instrumentation, or process configurations
Symbology
