ProMinent DULCOMETER diaLog DACb User Manual

The limit values are values that can be set within the measuring range of a measured variable. For
each measuring channel a Limit [1] can be set for exceeding, i.e. the measured value is greater than
the limit value and a Limit [2] can be set for undershooting, i.e. the measured value is less than the
limit value. As the controller only has two limit value relays, there is an option of selecting a limit
value ‘range’ . An upper and lower limit are set as a limit value ‘range’ . If the measured value is
above or below the ‘range’ , then a limit value transgression exists.
If the limit is exceeded for longer than the [Control time lim. val. (∆t on)] , then an error message is
triggered that has to be acknowledged and the alarm relay is deactivated. If the [controller] is also
set to [OFF] then the control process stops.
[Lower lim] means that the limit criterion has been transgressed by undershooting of the lower limit.
[High limit] means that the limit criterion has been transgressed by exceeding of the upper limit.
The controller has the option of defining [Hysteresis limit values] .
[Hysteresis] works towards rectifying the limit transgression, i.e. if the [Limit 1 upper] of, for example,
pH 7.5 has been exceeded by a set hysteresis limit of, for example, pH 0.20, then the criterion for
limit transgression is redundant when the value drops below the lower limit of pH 7.3. The hysteresis
behaviour for undershooting a [Low limit] functions in a similar way (here the hysteresis value is
added to the limit value). In this way it is possible to forego an external relay in self-retaining mode.
If the limit is exceeded for longer than the [Delay period limit values (∆t on)] , then an acknowledge‐
able fault message is triggered and the alarm relay is deactivated. If the [controller] is also set to
[OFF] then the control process stops.
Measured value
Limit value
transgression
Upper
limit value
"Hysteresis"
t
t
"Hysteresis“
Lower
limit value
A0009_GB
Fig. 93: Hysteresis
Setting the [Limit values]
139

ProMinent DULCOMETER diaLog DACb Specifications

General

Brand	ProMinent
Model	DULCOMETER diaLog DACb
Category	Controller
Language	English