Monitoring a Water Plant In Real-time

The worst way to find out about pump failure is to wait until a pump quits working.

The Sheboygan Regional Wastewater Treatment Facility, in Sheboygan, Wis., has five lift pumping stations. Maintenance personnel could do some monitoring of the remote stations, but not enough monitoring to catch motor-load conditions. They could tell if a pump failed, but they couldn’t monitor the pump’s deteriorating condition prior to failure.

Maintenance had to routinely go 30 feet below ground to check the health of pumps and motors. Sometimes, it was difficult to find the time for those visual and aural checks. Even then, workers couldn’t tell if a pump was partially constrained. “We weren’t able to monitor pump condition except by flow rate. The SCADA (supervisory control and data acquisition) system wasn’t looking at our motors directly,” says Dale Doerr, superintendent at Sheboygan Regional Wastewater. “It would have to go into total failure before there was any sign of a problem.”

To solve this, the plant operators replaced their bi-metallic overload relays with Motor Insight overload and monitoring relays from Cleveland-based Eaton Corp., in November of 2008. During the first month, the new tools detected conditions that might have resulted in motor or pump failure and energy waste—from a foreign object in a pump that was choking flow to a blockage in a valve. Plant operators can now monitor the entire system from headquarters.

The Eaton tools send the data to the facility’s SCADA system. “We have all the data from throughout the city streamed into the SCADA system,” says Steve Meifert, controls engineer at the plant. “Now it’s something our operators can look at on a daily basis and track the baseline. There is a threshold we can set on the unit and it will trip the alarm to let us know if something is going wrong.” He notes that the plant has fault codes and maintains code histories so operators can look back into previous fault codes to detect recurring deviations from system health.

While the data sharing is internal, it does travel across town so that it can be viewed from the plant’s headquarters. “We send the data over the Internet through an IP (Internet protocol)-encrypted tunnel,” explains Doerr. “It’s secure, but the network can get a little full. If we were to send a lot of data, it wouldn’t be as good, but it’s adequate for monitoring our remote locations.”

Soon after deploying the system, the Sheboygan plant found a number of pumps that were partially clogged and would eventually fail. The may have been caught before failure by a visual check. But maybe not. Even in their not-yet-failed state, they were already causing energy waste.

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