Electrical Process Instrumentation
Terms
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AUTOMATIC
CONTROL
SYSTEM - An operable arrangement of one or more automatic controllers,along with their associated equipment, connected in closed loops with one or more processes
- AMMETER
- An instrument used to measure current
- AMPERE
- A unit used to describe the rate of current flow
- ALARM
- A device or funtion that signals the existence of an abnormal condition by means of audible or visual discrete changes, or both, intended to attract attention
- ACCESSIBLE
- A term used to describe a device or function that can be seen by an operator for the purpose of performing control actions
- ACCURACY
-
Conforming to an indicated standard, or true value
(usually expressed as a percentage of span) -
BEHIND
THE
PANEL -
A term applied to a location that is within an area that contains:
1)the instrument panel
2)its associated rack mounted hardware
3)is enclosed within the panel -
BUBBLE
(BALLOON) - The circular symbol used to denote and identify the purpose of an instrument or function. It may contain a tag number
- BOARD
- A synonym for panel
- COMPUTER
- A device that performs mathematical calculations
- CHARACTER
-
A letter, digit or other symbol that is used as a representation of other data.
(a connected sequence of _________ is a ________ string). - CONTROLLING MEANS
- The elements in a control system that contribute to the required corrective action.
- CONTROLLED SYSTEM
- The part of the system under control, i.e. the process.
- CONTROL SYSTEM
- A system in which deliberate guidance or manipulation is used to achieve a prescribed value of a variable
- CONTROLLER
- A device that has an output that varies to regulate a controlled variable in a specific manner
- CPU
-
Central Processing Unit.
The portion of a computer that decodes the instructions,performs the actual computations, and keeps order in the execution of programs. - ELECTRICAL INTERFERENCE
- The electrical noise induced upon the signal wires that obscurs the wanted sigal information.
- HHARDWARE
- Physical equipment;eg. mechanical, magetic, electrical, or electronic devices.In essence, something you can touch with your finger.
- IDENTIFICATION
- The sequence of letters, or digits, or both, used to designate an individual instrument or loop
- INTRINSICALLY SAFE
- An Instrument that will not produce any spark or thermal effects, (under normal or abnormal conditions)that will igite a specific gas mixture.
- IMPEDANCE
- The total opposition to current flow (resistive and reactive)
- INSTRUMENT
- In process measurement and control this term broadly used to describe any device that performs a measuring or controlling function
- LOCAL PANEL
- A panel that is not a central or main panel
- LOCAL
- The location of an instrument that is neither in nor on a panel or console, nor is it mounted in a control room.The word "field" is often used in place of this term.
- LOOP
- A signal path. A combination of two or more instruments or control functions arranged so that signals pass from one to another for the purpose of measurement and/or control
- PANEL MOUNTED
- A term that applies to an instrument mounted on a panel or console and is accessible for the operator's normal use.
- PROCESS
-
The variable for which supply and demand must be balanced.
The system under control, excluding the equipment that does the controlling. - PILOT LIGHT
- A light that indictes the existence of a nuber of normal conditions for a system or a device.
- POWER SUPPLY
- A part of a system that supplies power to the rest of the circuit or system.
- PANEL
- A structure that has a group of instruments mounted on it, houses an operator process interface, and is choosen to have a unique designation
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PROGRAMMABLE LOGIC CONTROLLER
(PLC) - a controller, usually with ultiple inputs and outputs, that contains an alterable program.
- RELAY
- A device whose function is to pass on information in an unchanged form, or in some modified form.
- SIGNAL
- Information in the form of pneumatic pressure,electrical current,or mechanical position that carries information from one control loop component to another
- SWITCH
- A device that connects, disconnects, selects, or transfers one or more circuits and is not designated as a controller, relay, or control valve.
- SYSTEM
- Generally refers to all coponents, including process measurements, controller, operator, and valves, along with any additional equipment that may contribute to its operation
- TAG NUMBER
- An alphanumeric string used to identify an instrument or loop
- TRANSMITTER
- A device that senses a process variable through the medium of a sensor and has an output whose steady-state output varies only as a predetermined function of the process variable
- ANSI
- American National Standards Institute
- O.D.
- Outside Diameter