West Control Solutions ProVU 4 - Manual (Page 143)

ProVU4 Controller, Profiler & Recorder/Controller - Product Manual
Page 142 Glossary 59407, Issue 1 – March 2008
Input Span
The measuring and display limits, as defined by the Scale Range Lower and Scale Range
Upper Limits. The trimmed span value is also used as the basis for calculations that relate to
the span of the instrument (e.g. proportional bands).
Settings = 100 LSD’s to the full Input Range.
Default value = Input Range
Also refer to: Input Range, LSD, Primary Proportional Band, Scale Range Lower Limit, Scale
Range Upper Limit and Secondary Proportional Band.
Integral Time Constant
The Integral Time Constant biases proportional control output(s) to compensate for process
load variations, until the control deviation value is zero. Integral Time Constant is also known
as “Automatic Reset”. Decreasing the time constant increases the Integral action. This
parameter is not available if the primary output is set to On-Off.
Settings = 1 sec to 99 min 59 sec and OFF.
Default value = 05:00
Also refer to: Control Deviation, On-Off Control, PI Control, PID, Primary Proportional Band,
Secondary Proportional Band, Derivative Action, and Tuning.
Latching Relay
A type of relay that, once it becomes active, requires a reset signal before it will deactivate. If
latching relays are required, they can be fitted externally as slaves to the internal (non-
latching) relays of this instrument.
Also refer to: Relay
LED
Light Emitting Diode. LED’s are used as indicator lights (e.g. for the alarm indication,
automatic tuning stats and manual mode).
Also refer to: Alarm Operation, Alarm Types, Automatic Tuning and Manual Mode.
Linear Input
A mVDC, mADC or voltage signal used to represent the value of the process variable. This
can be any variable that can be converted into a suitable DC linear signal. Common
examples are Humitity, pressure, pH or temperature.
Auxiliary linear inputs can also be installed, these can be used to provide a remote setpoint.
Also refer to: Auxiliary Input, Input Range, Linear Output, mVDC, mADC, Process Variable,
Remote Setpoint and VDC.
Linear Output
A mVDC, mADC or voltage signal used to provide a proportional control or retransmit output.
Also refer to: Linear Input mVDC, mADC, Proportional Control, Retransmit Output and VDC
Limit Controller
A safety protection device that will shut down a process at a preset “exceed condition”. Limit
controllers work independently of the normal process controller in order to prevent possible
damage to equipment or products. They are recommended for any process that could
potentially become hazardous under fault conditions. A fail-safe latching relay is fitted, which
cannot be reset by the operator until the process has returned to a safe condition.
Also refer to: Controller and Latching Relay.