STRADA proves its worth

Without expensive upgrades, many existing SCADA systems cannot supply the level of data required to understand asset performance. Now, Stirling Technical Engineering has developed a solution to the problem.

Existing market pressures and the current economic climate are creating a step-change in organisational management of remote assets that has not only seen a reduction in direct employed manpower but also an increase in outsourcing of remote asset maintenance.

This trend is likely to continue with the transfer of private sewers and pumping stations to water companies.

Recently, Stirling Technical Engineering (STE) has seen an increase in requests to obtain better data from remote assets from users who have become frustrated at the lack of available data from their legacy SCADA systems.

Unfortunately, many SCADA systems were installed to provide a level of data and functionality that met the operational needs and structure of the organisation that was present at the time of installation. As such, many legacy SCADA systems are reactive and alarm-based storing limited data.

Such systems often place demands on resources to react to alarms, however in today’s climate of de-manning, re-structuring and streamlining, such resources are becoming rarer.

Mike Ward, senior project manager for Stirling, comments: “As a specialist telemetry contractor, Stirling are now seeing an increased trend in the need to identify ways of proactively managing and improving asset performance.

“Unfortunately, without large expensive upgrade programmes, many legacy SCADA systems cannot provide the level of data required to understand asset performance or assist with a move towards more proactive management of these assets.”

To tackle this problem, Stirling has developed the STRADA (Stirling Technology Remote Asset Data Acquisition) system.

STRADA works by using Stirling’s extensive knowledge of existing SCADA systems and coupling this with modern GPRS-enabled, battery-powered data loggers and web-based software. STRADA allows data to be collected and transmitted from existing equipment on remote sites without impacting on existing telemetry infrastructure or asset performance. Stirling have partnered with Detectronic, a Lancashire-based logger manufacturer to provide battery powered loggers which can be used to record data from up-to eight digital or analogue outputs for each site, such as analogue level, flow or digital inputs such as pump running/stopped.

The loggers, which are installed by Stirling Engineers interface with signals before the outstation and can record data at intervals as little as every 30 seconds. The GPRS modem integrated into the logger allows data to be sent off site directly to Stirling’s servers, at a programmable time period but typically is set at once per day.

The STRADA web-interface has been designed to allow users to assign data types to each of the eight possible outputs being logged and the graphical data viewer automatically groups these data into types for easy comparison. (Screenshot from STRADA system)

During AMP4, Stirling configured and commissioned more than 300 electro-magnetic (EM) flow meters at sewage pumping station (SPS) sites to provide an indication of a potential rising main burst or blockage by generating a derived alarm based on a high or low flow being recorded. Whilst crude, this derivation was an accepted limitation of the existing telemetry system.

Stirling has also been working over the past three years to retrofit more than 200 Pulsar Quantum pump controllers into SPS sites to provide a pump auto-reset function to reduce the amount of call-outs to reset failed pumps.

Recent developments by Pulsar on the Quantum pump controller now include an analogue flow output which uses an in-built algorithm to derive a flow rate based on the rate of change in the well level. In August 2010, Stirling used the STRADA system to examine the potential for using the Pulsar Quantum to provide flow data for SPS sites instead of installing EM flow meters.

Stirling engineers installed STRADA at ten SPS sites with existing EM flow meters and Quantum controllers for a

period of three months.

The signals that were logged included analogue flow output (l/s) from the EM flow meter, analogue flow (l/s) and wet well (m) outputs from the Quantum controller.

In addition, pump running/standing signals were also logged to assist in the analysis of the data. The STRADA system was set-up to log data from all outputs at two-minute intervals and send the data to Stirling’s severs on a daily basis.

Prior to the trial it was identified that a potential limitation of using a derived flow would be where rapid or no changes would occur in the wet well such as times of storm or surcharge.

Initial analysis of the data from the STRADA system indicated that the Quantum controller flow was within 1.8l/s and typically read lower than the EM flow meter.

Pulsar used the initial data collected from STRADA to improve the performance of the Quantum flow algorithms to within 0.7l/s of the EM flow meter. Distribution patterns generated from the STRADA system show excellent correlation between the EM flow meter and Quantum.

“The STRADA system has been invaluable in assisting us to fine tune the real time flow algorithms within the Quantum controller. This has given increased accuracy readings over all inflow conditions,” says Alistair McKinnon, sales manager for Pulsar.

Following the installation of STRADA, Stirling are continuing to work with Pulsar on the development of algorithms to provide intelligent burst and block alarms from the Quantum controller based on instantaneous, pump cycles, flow rates and instantaneous flow rates an improvement over existing methods.

“The use of STRADA has identified a potential cost saving of around £3.6M by changing from a strategy that used EM flow meters to Quantum controllers and also assisted Pulsar in developing the Quantum using real site data,” says Ward.

“A rare win-win-win situation for supplier, contractor and client.”

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