IT, SCADA AND TELEMETRY
Remote control
Alan Wood, managing director of Wood and
Douglas, takes a look at the latest innovations
in IT, telemetry and Scada for water utilities
T
he increasing regulatory demands on utilities to deliver
clean water and safely dispose of wastewater is significant
and growing, yet the technical environment in which
they work has never been more complex or demanding.
The issues are many and varied: how to fulfil demand for water
successfully, how to guarantee quality across the infrastructure, and how
to manage operating costs. From river resource and industrial discharge,
through to the operation and management of 300,000km of sewers
Sentinel digital data telemetry
radios are designed for data transmissions
and over 9000 wastewater treatment works spread across the entire
applications within SCADA systems, supporting
UK landscape, wireless technology is becoming increasingly important
both point-to-point and point-to-multi-point operation.
in linking sites in the physical world to utilities’ connected networks.
It helps improve communication to deliver constant, high-quality extra data adds loading to existing analogue radio systems, which means
monitoring, no matter how remote the location, without incurring that the time required to poll all of the outstations takes longer. As a
high costs across the life of the system. result any problems can take longer to be identified in the control room.
Digital not only alleviates this loading but the new digital radio modems
Digital revolution crucially offer a data encryption facility, with the options of AES128 bit and
Traditionally water monitoring has been challenging due to the limitations AES256 bit encryption, to ensure unauthorised interception and decoding
of analogue wireless systems, limited security and maintenance issues of the data polls and responses is made impossible.
varying from failing signal strength to service outages, as dormant
problems lead to breakdowns. Fortunately, new developments in digital Managing the flow of information
telemetry and SCADA (Supervisory Control And Data Acquisition) One of the greatest advantages in terms of telemetry and Scada is in the
technology mean that water utilities across the UK and Ireland now have capability of modern digital radio modems to incorporate Network
more effective means to diagnose faults remotely and to monitor the Management System (NMS). NMS directly responds to the cost issues
performance and protect the value of remote assets. incurred from loss of monitoring and resultant service calls. It enables
technicians to monitor the health of every radio in their scheme from
“One of the greatest advantages in terms
their desk rather than having to make regular site visits.
The latest Network Management Systems are importantly non-
of telemetry and Scada is in the capability intrusive, so do not impact on the SCADA data traffic flow, but still
of modern digital radio modems to
automatically transmit back to the control room important radio
parameters that are constantly monitored and logged on a ‘diagnostics’
incorporate Network Management Systems” computer server. The parameters reported from each outstation include:
received signal strength, antenna VSWR, forward power, reflected power,
Analogue radio modems typically operate at 1200bps over-air data DC voltage, radio temperature, frequency drift, and the number of good
rate; the latest digital radio modems operate at 9600bps on exactly the and bad data packets received.
same radio channels. This higher data rate is crucial when deploying UHF
SCADA radio systems that use a ‘polling’ method. The Master radio, Early warning system
usually high up on a hilltop, transmits requests to outstation locations and As the NMS compares the data from all these parameters it can provide
receives responses containing the current Remote Terminal Unit (RTU) early warning of developing problems before a complete outage renders
values. The RTU, a monitoring device for key data, such as water pressure, the monitoring system unusable. Simple issues, such as an antenna
levels and temperature, interfaces the physical world of the water utility being blown off direction, which occasionally happens, or water entering
to a distributed control system (DCS). the antenna coaxial cable, causing attenuation of the transmit and
Digital technology allows the Master station to poll around the water received signal strengths, can now be rapidly identified and addressed to
utility’s outstations far faster, with a reduced polling interval. One at a ensure Scada and telemetry operate at maximum capacity with minimal,
time each outstation radio is polled. When each outstation has been targeted maintenance. That translates into major cost savings as
polled the sequence starts again, and running continuously 24 hours a maintenance crew schedules are made more efficient and works are
day, 365 days a year. All the SCADA data is read faster and outstation addressed before problems escalate.
problems are identified, with no data traffic costs. The goal of all water treatment processes is to remove existing
contaminants in the water or reduce the concentration of such
Security concerns contaminants so the water becomes fit for its desired end-use. New
As scrutiny of security implementation heightens, water utility companies techniques in radio signaling transmissions help to deliver the flow of
now have to add extra monitoring points to their outstation RTUs to crucial monitoring data 24/7, ensuring that issues are addressed quickly
detect, for example, the opening and closing of an access hatch. This and at an effective cost. ■■■
November 2009 Water & Wastewater Treatment 25
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