8 Set Points
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The output relay now operates by producing a series of pulses of fixed duration.
The pulse rate increases as the measurement moves further from the set point,
until it reaches the maximum frequency at the limit of the proportional band. (i.e. 4
ppm in the previous example).
DOSE ALARM TIMERS
The dose alarm timer can be used to prevent overdosing under many different fault
conditions , such as sensor failure or wiring faults. When the timer is enabled the
user can set the “Alarm Time”. If the associated relay remains energised for
longer than the “Alarm Time” the alarm will activate, de-energising the relay to
prevent over-dosing and flash the relative set point LED on the front panel. The
display will also flash a warning message when the alarm is activated. NB During
pulse or time proportional operation the cumulative “on” time that the set point is
active will be taken.
To cancel the warning, and reactivate the set point, the user need only press the
“ENTER” button on the front panel. NB. If more than one Alarm is active, set point
1 takes priority over set point 2 which takes priority over set point 3, and they are
cancelled in that order by additional presses of the “ENTER” button.
Set Point 4 can be set to activate when a Dose Alarm is detected.
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