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New consent
regulations are the main drive behind Northumbrian Water's major
capital investment at Howdon. Significant improvements have been
made to the wastewater processing and management at the site, which
sits on the bank of the river Tyne.
New Control System
As part of the
overall improvements strategy, a new Supervisory Control and Data
Acquisition (SCADA) system has been supplied by a national based
Systems Integrator, Aston Dane plc. The system, comprising over
3500 signal data inputs and outputs which control and monitor all
aspects of the process operations, utilises state of the art fibre
optic technology for the site wide transmission of data.
There are three
layers of networking incorporated in to the design of the new system.
At the 'operational and management information' layer, a redundant
Hirschmann RS2™
fibre optic Ethernet ring is installed for communications between the
Serck SCX™
Server machines and the field mounted industrial SCADA clients.
The 'process
control' layer employs two Rockwell ControlNet™
fibre networks run via different routes (for redundancy purposes)
across the site and connects the Rockwell PLC's to the Serck SCX
Servers.
DeviceNet
The
'field' layer, (the equipment or device control level) is supported by
proprietary DeviceNet™,
which links the redundant PLC's to over 200 motor drives, ranging in
size from 1.1kW to 200kW and includes in addition to direct on-line
drives, reversing, soft-start and variable speed arrangements.
Unusual Feature
The Treatment Works surrounds
the Chemson paint factory. This presented additional control and
monitoring constraints in that hydrogen sulphide (a potential emission
from the sludge treatment process) can cause discolouration of the
paint manufactured in the Chemson factory. To overcome this problem,
wind speed and direction measuring instrumentation has been installed
in addition to hydrogen sulphide monitors. Data is transmitted
to the SCADA workstations to assist the operators in the control of
any problem that may arise.
To provide greater security,
critical plant data is transmitted via radio to the Northumbrian Water
Regional Telemetry system using two Rockwell programmable interface
modules connected by DF1™
links to on site PLC's.
Online
Documentation
Another innovative feature
enabled by new NT technology is access to critical maintenance
documentation directly from links on the plant mimics.
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