Automated Controls - Glossary

Question 1

How an indicated value conforms to an accepted standard value or true value.

Answer 1

Accuracy

Question 2

Analog to digital converter

Answer 2

ADC [A/D]

Question 3

A signal representing a variable which may be continuously observed and continuously represented.

Answer 3

Analogue signal

Question 4

A decrease in signal magnitude. Also, the reciprocal of gain.

Answer 4

Attenuation

Question 5

A signal path which includes a forward path, a feedback path, and a summing point, and forms a closed circuit.

Answer 5

Closed loop

Question 6

The parameter that is desired to be controlled. e.g. temperature, flow rate, pressure, liquid level.

Answer 6

Controlled/process variable

Question 7

A device which operates automatically to regulate a controlled variable.

Answer 7

Controller

Question 8

Digital to analogue converter

Answer 8

DAC

Question 9

Digital control system

Answer 9

DCS

Question 10

Distributed (Direct) Digital Control - A building automation system in which a microprocessor based control system performs building automation digitally.

Answer 10

DDC

Question 11

The range through which an input can be varied without initiating an observable response.

Answer 11

Dead-band

Question 12

Control action in which the output is proportional to the rate of change of the input.

Answer 12

Derivative (rate) control action

Question 13

Information represented by a set of binary numbers.

Answer 13

Digital signal

Question 14

In a control loop, it is the variable which is sensed to originate a feed-back signal.

Answer 14

Directly controlled variable

Question 15

Information represented by a set of separate and distinct numbers or values.

Answer 15

Discrete signal

Question 16

A component of a device or system

Answer 16

Element

Question 17

This is the signal derived in a closed loop control system from the difference between the set-point signal and the feed-back signal.

Answer 17

Error signal

Question 18

The return signal which is generated from the measurement of the directly controlled variable.

Answer 18

Feed-back signal

Question 19

It is the forward controlling element which directly changes the value of the manipulated variable.

Answer 19

Final control element

Question 20

The ratio of the change in output due to proportional control action to the change in input.

Answer 20

Proportional gain

Question 21

Control action in which the output is proportional to the time integral of the input.

Answer 21

Integral (reset) control action

Question 22

A quantity of condition which is varied as a function of the actuating error signal so as to change the value of the directly controlled variable.

Answer 22

Manipulated variable

Question 23

Resistance and temperature are inversely proportional.

Answer 23

NTC - Negative temperature coefficient

Question 24

A signal path without a feedback.

Answer 24

Open loop

Question 25

Physical or chemical change of matter or conversion of energy. e.g. change in temperature, pressure, temperature, electrical potential, speed, etc.

Answer 25

Process

Question 26

Control action in which there is a continuous linear relation between the output and the input.

Answer 26

Proportional control action

Question 27

Resistance and temperature are directly proportional.

Answer 27

PTC - Positive temperature coefficient

Question 28

The region between two limits within a quantity is transmitted, measured or received.

Answer 28

Range

Question 29

The smallest interval between sequential discrete values. e.g. the number of degrees per address produced by an absolute encoder.

Answer 29

Resolution

Question 30

The element which directly responds to the measured variable.

Answer 30

Sensor (sensing element)

Question 31

An input variable which determines the desired value of the controlled variable. It may be manually set, automatically set or programmed.

Answer 31

Set-point

Question 32

The algebraic difference between the upper and the lower range values.

Answer 32

Span

Question 33

A device element which converts energy from one type to another.

Answer 33

Transducer

Question 34

A transducer which responds to a measured variable by means of sensor (sensing element) and converts it to a standardized transmission signal.

Answer 34

Transmitter