Manual
Restart:
RTD:
Set
point:
Signal
conditioner:
Single
.mode
cont
rol
:
Span:
Switching
sensltlvlty:
Thermal system:
Thermocouple:
Thermocouple
break
protection:
Three mode control:
Time-In-step:
Time Proportioning
Control:
Trlac:
Solid state switching device.
Two posltlon
control:
An ON/OFF control.
Warm
Start:
Start-up condition where all program information is remembered by the
instrument’s memory back-up protection.
In the Series 1500, powering up
with
Dip Switch
#6
in the OFF position gives a “Warm Start.”
Wet Bulb:
Zero
switching:
To begin to control a thermal system again, after stopping control and holding
the process variable at a
fixed
value. A “restart” may occur with
newly-
programmed information in microprocessor-based controls.
Resistance
Temperature
Detector.
Resistive sensing device displaying linear
resistance versus temperature characteristics.
Displays positive temperature
coefficient.
Intended value of the process variable.
An electronic circuit that provides sensor compatibility of the input signal for use
in the control. Includes linearization and/or sensor
excitiation.
Proportioning control.
Distance in degrees or other units between the minimum and maximum
operating limits of a sensor or
controller.
See
"Hysteresis."
A regulated environment consisting of a heat source, heat transfer medium,
sensing device and a process variable control instrument.
Temperature sensing device that is constructed of two dissimilar metals
wherein a measurable, predictable voltage is generated corresponding to
temperature.
Fail-safe operation that assures output shutdown upon an open thermocouple
condition.
Proportioning control with auto-reset and rate.
Time remaining in any given
program
step.
Action which varies the amount of ON and OFF time when “close” to the set
point, i.e., in the proportional band. This variance is the result of the control
algorithm.
In other words, the amount of time the output relay is energized
depends on the system control requirement.
Half
of
a
wet
bulb/dry bulb %RH sensor system, i.e., an RTD with a wet sock.
Action
which provides output switching only at the zero
voltage
crossing
points
of the AC line.
88
WATLOW Series 1500
User's
Manual
Glossary, Appendix