Glossary
A-20
Appendix 6
535-PROF User's Manual
proportional band:
The change in
input required to produce a full range
change in output due to proportional
control action.
ramp:
A rise or fall of the setpoint in a
given segment. Ramps may be
defined by the time it will take for the
setpoint to be achieved or the rate of
rise or fall necessary for the target
(soak) setpoint to be achieved.
rate:
Anticipatory action that senses
the rate of change of temperature and
compensates to minimize overshoot.
Also “derivative.”
rate action:
The derivative function of a
controller.
rate time:
The time interval over which
the system temperature is sampled for
the derivative function.
regulate:
The act of maintaining a
controlled variable at or near its
setpoint in the face of load
disturbances.
relay (mechanical):
An
electromechanical device that
completes or interrupts a circuit by
physically moving electrical contacts
into contact with each other.
relay (solid state):
A solid state
switching device which completes or
interrupts a circuit electrically with no
moving parts.
reset:
Control action that automatically
eliminates offset, or “droop,” between
setpoint and actual process
temperature. Also “integral.”
reset term:
(see reset)
RTD:
Resistance Temperature
Detector. Resistive sensing device
displaying resistance versus
temperature characteristics. Displays
positive temperature coefficient.
relative gain:
An open-loop gain
determined with all other manipulated
variables constant, divided by the
same gain determined with all other
controlled variables constant.
retransmission:
a feature on the 535
which allows the transmission of a
milliamp signal corresponding to the
process variable, target setpoint or
actual setpoint to another devices,
typically a chart recorder.
sample interval:
The time interval
between measurements or
observations of a variable.
secondary loop:
The inner loop of a
cascade system.
self tune:
A method of automatically
calculating and inserting optimum PID
parameters by testing system response
and timing.
serial communications:
The sending
or receiving of binary coded data to a
supervisory device such as a personal
computer of programmable logic
controller.
setpoint:
An input variable which sets
the desired value of a controlled
variable.
setpoint, actual:
The desired value of
a controlled variable that the controller
is currently acting upon.
setpoint, deviation from:
The number
of units difference between the current
process variable and the setpoint.
setpoint, ramping:
A setpoint which is
determined by the ramp function of the
controller where over time the
controller variable reaches a desired
value.
setpoint, target:
The end point of the
ramp function.
set up:
Also called configuration,
selection of hardware devices and
software routines that function together.
sheds:
In serial communications, when
the signal is lost.
slidewire position proportioning:
An
output algorithm that utilizes a slidewire
feedback signal to determine the actual
position of the actuator being controller.
soak:
Also called "dwell.: The
designated period of time in which
the setpoint does not change after the
ramp has been completed.
soak, guaranteed:
Guaranteed soak
insures that the soak setpoint has
been achieved before the soak
segment starts.solid state relay: (see
relay, solid state)
SSR drive:
A D.C. on/off signal output
for controlling a solid state relay.
staged outputs:
The set up of two
analog outputs, where one analog
output varies its signal over a portion of
the PID output range, and the second
analog output then varies its signal
over the remainder of the PID output
range.
static discharge:
Undesirable current
resulting from the discharge of
electrostatic energy.
station address:
The unique identifier
assigned to a device for
communications.
thermocouple:
Temperature sensing
device that is constructed of two
dissimilar metals wherein a
measurable, predictable voltage is
generated corresponding to
temperature.
thermocouple break protection:
Fail-
safe operation that assures desired
output upon an open thermocouple
condition.
thermocouple upscale burnout ( ):
Jumper position that determines
whether, when a thermocouple fails, its
output is replaced by a millivoltage
which will match the thermocouple’s
maximum value. The jumper connector
should be placed in the TC s position.
thermocouple downscale burnout ( ):
Jumper position that determines
whether, when a thermocouple fails, its
output is replaced be a millivoltage
which will match the thermocouple’s
minimum value. The jumper connector
should be placed in the TC t position.
