How can water companies reduce storm overflow discharges? (Part 3)

In part 1 and part 2 of this series, we discussed strategies to help water companies eliminate storm overflow discharges. This focused on the benefits of using low-CAPEX solutions such as condition monitoring techniques as part of a combined low-CAPEX/high-CAPEX strategy. The proposed approach would allow water companies to reduce environmental impact, lead times and public disruption, as well as meet storm overflow targets much quicker. It would also deal with factors such as pump clogging that high-CAPEX options like green infrastructure don’t usually address. In this final article in the series, we will dive into details of the unique benefits that electrical signature analysis technology provides to water utilities.

What is electrical signature analysis?

Electrical signature analysis (ESA) is a condition monitoring technique that analyzes current and voltage data. It’s based on the fact that subtle changes in a machine’s operation affect the connected motor’s magnetic field, which then affects the supply voltage and operating current. To uncover developing failures, ESA technology uses a variety of analytical techniques to provide a detailed asset health picture across the drivetrain, from motor to transmission to load (such as pump, conveyor, mixer and other driven equipment).

The technique has a long track record. It was first developed by Oak Ridge National Laboratories in the 1980s to safely monitor motor-operated valves in a nuclear power plant. Since ESA measures the voltage and current being supplied to the motor driving the valve, it could accurately track the whole machine’s health. And because ESA captures electrical signals, its sensors are non-invasive current and voltage probes that install around the phase wires in the motor control cabinet, not on the machine itself.

The unique benefits of ESA

The characteristics of this condition monitoring technique provide many advantages for water companies which can be leveraged to reduce storm overflow discharges on the pathway to 2050. Below are several key ways ESA-based technology can be applied:

Detecting pump blockages, a major cause of pollution events:

As already mentioned, ESA can pick up faults along the full drivetrain, because each fault will influence the electromagnetic field surrounding the electric motor that is driving a pump. The same applies to pump clogging, which also produces a specific signature in the current and voltage data. When this is combined with knowledge of the machine’s geometry and real-time analysis, it can help ESA systems detect and localize pump blockages at an early stage.

Having a tool to detect clogging events in real time would enable utilities to quickly intervene and resolve pump blockages before they cause a pump failure and a potential pollution to the local environment. ESA-based systems could therefore become an important part of a hybrid strategy to reduce combined sewer overflow (CSO) discharges and help meet regulatory targets early on.

Remote and real-time monitoring in challenging environments:

ESA sensors collect electrical data via non-invasive current and voltage probes installed in the motor control cabinet, not on the equipment itself. That means ESA provides a way to capture accurate and usable asset health data remotely and in real time, without the need for regular pump station visits to lift a pump. This is a great advantage for the wastewater industry where most assets are submerged as it would enable companies to use data-driven insights to maintain critical equipment and be proactive in their asset maintenance strategy.

Quick implementation leading to quick results:

The location of ESA sensors in the motor control cabinet provides for relatively quick and simple implementation/operation compared to other techniques which require visiting pumps across an entire network to perform asset diagnostics. This also implies a solution that can be implemented at a lower cost, and that results can be generated quickly. Through the detection and resolution of asset failures and clogging events at an early stage, water companies can also quickly start reducing the number of pollution events and CSO spills. In addition, by detecting developing faults remotely in real time, water utilities could mitigate the need for cyclical visits to pump stations to check on pump status. This would save a significant amount on financial and environmental costs.

Improving network efficiency through pump performance optimization:

ESA can be effectively utilized to increase network efficiency by improving pump performance. Detecting and resolving developing faults at an early stage already improves network efficiency as it prevents catastrophic failures and saves energy (a failing pump will be using more energy compared to a healthy one). In addition, an ESA-based system can identify underlying inefficiencies by comparing the pump’s actual operation to its desired operation, which occurs at or near its best efficiency point (BEP). The pump affinity laws enable ESA systems to transform their current and voltage measurements into accurate estimates of real-time power, head and flow.

This information can help utilities to correct a pump that’s operating significantly away from its BEP, which lengthens the life of the asset and reduces operational risks. Real-time insight can help in decision-making, from scheduling immediate corrective actions to implementing long-term process changes. For example, it can be used to identify where equipment may be set up incorrectly or be oversized for purpose. Rectifying such issues could further help to raise reliability and save energy.

ESA in industry

ESA is already being widely used in the water industry, helping companies to move toward a more proactive maintenance strategy and successfully tackle pump blockages, and in turn potential pollution events. Only recently UK-based Yorkshire Water chose to extend its use of ESA monitoring to cover its complete wastewater network. Below is an example of how an ESA-based system from Samotics is being leveraged in real life within the water industry: