Proportional Band:

A controller parameter setting which

determines the change in the number of

engineering units of a process variable input

signal that will produce a full-scale change of

the controller analog output signal.

Proportional (P) Mode:

Control mode in which there is a continuous

linear relationship between the input and the

output.

Proportional-Integral (PI) Mode:

Control mode in which the output is

proportional to a linear combination of the

input plus a value proportional to the time

integral of the error between setpoint and

control point.

Proportional-Integral-Derivative (PID) Mode:

Control mode in which the output is a value

proportional to the input, plus a value

proportional to the time integral of the error

between setpoint and control point plus a

value proportional to the time rate of change

of the error.

PSI:

Pounds Per Square Inch

PSIA:

Pounds Per Square Inch, Absolute

PSID:

Pounds Per Square Inch, Differential

PSIG:

Pounds Per Square Inch, Gauge

PV:

Process Variable

R:

RA:

Return Air

Range:

The upper and lower limits of the value of a

variable.

Ratio:

A single-loop digital controller feature which

multiplies the remote setpoint input signal to

the controller by a constant and uses the

resulting value as the controller setpoint.

An electric device that changes the position

of its contacts when its coil is energized.

Remote Setpoint:

See Control Point Adjustment.

Resistance Temperature Detector (RTD):

A device whose resistance changes linearly

as a function of temperature.

REV:

Reverse-Acting

Glossary-10

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