Application Note 13
CSO Monitoring
The
European Water Framework Directive (WFD), which came into force across
Europe in December 2000, places an obligation on water companies to
monitor waste water discharges through Combined Sewer Outflows (CSO’s).
This introduces a requirement for specific telemetry equipment for
installation at small unpowered sites, to monitor the water level and/or
flow, report it at regular interval, and report alarm conditions.
Most
water companies ultimately need to pass the data into a central computer,
which will log it and generate appropriate alarms and reports. In
some cases this will be an existing regional telemetry system, in others
it may be a dedicated computer system.
Churchill
Controls are addressing this requirement in three phases:
1.
Use battery-powered Nano_Link outstations, packaged with appropriate
transducers, to relay the relevant readings to a Micro_Link base-station
via de-regulated radio, which will then pass the data into a third-party
regional telemetry outstation. The regional telemetry system will
therefore receive ‘live’ data which it can process as required.
This solution can be constructed from existing products, with no special
development. It assumes there is a regional telemetry outstation within
radio range. If the application allows aerials to be mounted on
masts the range could be up to 20Km. If the aerials are restricted
to ground level the range could be up to about 5Km. If the aerials
have to be installed below ground level, the range will be limited to
about 500m. However, the range can be extended if provision is made
for radio repeaters at appropriate locations.
2.
Develop a variant of the existing product using a GSM cellular radio modem
in place of the de-regulated radio, packaged with appropriate transducers.
Provided the outstation is within range of a GSM base-station the data can
be passed to a telemetry base-station and/or mobile telephones located
anywhere. A base-station is being developed as a software package to
run on a PC. The base-station will retrieve the data from the
outstations and pass it to a third-party software package via a standard
software interface. The third party package could be either an
existing regional telemetry system base-station or a SCADA system.
3. Both of the above solutions will use the existing outstation hardware design, and conventional transducers. The third phase will be to derive a dedicated product, optimised for this application, combining the transducer and the telemetry outstation into a single product. This will offer the opportunity for cost and size reduction, and may allow the battery life to be further optimised.