Limit Indicator - wtw DIQ/S 182-MOD System Operating Manual

System 182
Function
Settings
ba75504e07 04/2012

6.4.4 Limit indicator

The characteristic of the limit indicator is laid down in the Limit value
UL, Limit value LL, Hysteresis UL and Hysteresis LL settings. The
fundamentals of the function are described in the introductory chapter
(see section 6.3.2).
In order to set up the Limit indicator function for a relay output, the relay
output must be linked with a sensor (see section 6.2.1).
Setting
Limit values
Limit value UL
Limit value LL
Hysteresis UL
Hysteresis LL
Behavior at error
Action
Switching delay
Selection/Values
UL main variable
LL main variable
UL adjoining var.
LL adjoining var.
within the
measuring range
(sensor-dependent)
0 - 10 % of the
measuring range
Open
Close
Unchanged
Open
Close
0 ... 3600 s
Relay outputs
Explanation
Main variable
designates the actual
measured parameter of
the sensor (e.g. pH,
oxygen, etc.).
Adjoining variable
designates an additional
measured parameter
(e.g. temperature).
Any upper or lower
limiting value
Hysteresis for upper or
lower limiting value
The relay opens, closes,
or remains unchanged in
case of system errors or
sensor errors (see page
6-25).
Relay action
The time period for
which a limiting value
must be exceeded
before the relay
operates.
Prevents frequent
switching for measured
values that are close to
the limiting value.
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