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Single or two-stage control can be performed with a third output
available to control an additional valve or pump. To ensure maximum accuracy,
overrun compensation may be selected to automatically minimise batching errors
caused by actuator delays.
The backlit display is readable in all lighting conditions.
The user screen may be selected so that the operator is only presented with
essential process information. Variables that may be displayed include dispensed
quantity, batch setpoint, rate of dispensing and controller status. Most of the
standard display screens also include a bargraph showing batch progress. A
record of total product dispensed is maintained as a grand total together with a
history of the last ten batches.
Up
to nine setpoints may be
pre-entered and selected by the operator when required. To simplify selection,
each setpoint may be identified by a plain language name having up to sixteen
alphanumeric characters.
The three isolated outputs are individually configured as
control or status outputs. If more are required, a factory fitted option
provides three additional identical isolated outputs.
Front panel push buttons allow the operator to start and stop the
batch and to reset the controller at the end of each cycle. For applications
where large or remote push buttons are required, control may be transferred to
external switches with or without inhibiting the front panel controls.
Counting may be inhibited during a batch by closing an external
contact. Thus product may be re-cycled whilst being heated, or the batching
system may be purged without affecting the quantity dispensed.
Selectable automatic restart causes the batch controller to
execute the batching operation a pre-set number of times. The delay between
batches may be set between 1 second and 24 hours, thus enabling the controller
to perform regular dosing and sampling operations.
ATEX
certification permits the
batch controller to be installed in gas and dust hazardous areas. The magnetic
pick-off, voltage pulse and 4/20mA inputs comply with the requirements for
simple apparatus, allowing direct connection to most certified flowmeters.
Switch contacts and a wide range of certified proximity detectors may also be
directly connected to the batch controller. All three control outputs are
galvanically isolated and certified as separate intrinsically safe circuits with
output parameters complying with the requirements for simple apparatus. This
allows most certified hazardous area loads such as valves, lamps, and sounders
to be controlled, or the output may be transferred to the safe area via a wide
range of Zener barriers or galvanic isolators.
Controller configuration may be performed via the front panel
push buttons or optional external switches. To prevent accidental or
unauthorised adjustment, access to the configuration menus is restricted by an
external security link and an optional user definable four digit security code.
Supply overload protection prevents the batch controller being
damaged if it is directly connected to a dc supply without a Zener barrier or
galvanic isolator, thus eliminating a common cause of failure during
commissioning and maintenance.
The GRP enclosure has stainless steel fittings, neoprene
gaskets and an armoured glass window. The robust construction provides IP66
protection which has been independently assessed by ITS – report available. A
separate terminal compartment allows the instrument to be installed and
terminated without exposing the electronic assembly. To further simplify field
wiring and subsequent inspection, the terminal cable entries and clamping screws
are both forward facing.
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