BEKA BA458C, Manual

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7. CALIBRATION EXAMPLE
In this example a BA458C batch controller is
required to control the dispensing of a liquid
into a tank as shown in Fig. 17. It is a stand-
alone system so galvanic isolators have been
used for the interface between the safe and
hazardous area. The batch controller is
powered by an isolator with a 28V, 93mA
output safety description. Two more identical
devices are used to power the intrinsically safe
solenoid valves that are controlled by Control 1
and Output 2. Output 3, which is configured
as a flow alarm, is connected to a switch
transfer isolator which produces a switch
contact closure in the safe area.
The BA358C batch controller is required to:
Dispense 1,000 or 500 litres of product into
a tank having a maximum capacity of
1,100 litres. Two volumes to be identified
Full volume and Half volume respectively.
The flowmeter incorporates a proximity
detector and produces an output of 25
pulses per litre.
Display the dispensed total with a
resolution of 0.1 litres.
Batch Controller to count upwards from
zero to the batch setpoint.
Control two parallel valves (2 stage
control).
At start of the batch valve 2 is to open 10
seconds after valve 1 and to close when
50 litres of product remain to be
dispensed.
Compensate for errors resulting from
actuator delays.
Initiate an alarm if the flow rate falls below
0.2 litres per second. Alarm to be
inhibited for the first 20 seconds of the
batch.
Operator needs to select the batch size
from the operator menu, but must not be
able to adjust the two setpoints. The
operator requires access to the history of
the last ten batches but must not have
access to the configuration menu.
The process is to be controlled by the
batch controller’s front panel switches. The
Reset function is not required.
The Operator Menu is not to be protected by a
security code, but the Configuration Menus are
to be protected by code 1209.
Fig 17 Liquid dispensing system
System Settings
Function Setting
Language English
User Controls Local
Signal Input Prox Detector
Lineariser Off
Restart Quick
Output 2 Control 2
Output 3 Flow Alarm
Clear Grand Total Yes
Security
Config Code 1209
Operator Code 0000
Operator Menu Batch Sizing Off
Batch Select On
History On
Config Menu Off
Operator Screens Screen 1