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WHERE WATER & ELECTRICITY MEET: REMOTE WATER METER READING

by TOM KNUTSEN & BRYAN SANDERSLOWER COLORADO RIVER AUTHORITYPublished in UTILITY AUTOMATION & ENGINEERING T&D MAGAZINE, JULY 2006

Our idea was simple -- we’d transfer our technology and skills from metering electricity use to measuring water flow. Our goal was to adapt the electric utility industry’s methods for collecting and managing meter data from remote meters to the Lower Colorado River Authority’s (LCRA) water businesses. We are currently reading two wholesale water meters remotely. To do that, we did more than transfer methods; we created new links between equipment and software that had never before talked with each other. We wanted to collect water pulse data into our electric utility standard meter reading software, Itron’s MV-90.

LCRA, an agency of the state of Texas created in 1934 by the legislature to manage soil and water of the lower two-thirds of the Colorado River, is also a generation and transmission electric utility. It sells electricity wholesale in 30,000 square miles of central Texas to public distribution systems. LCRA also sells both treated and raw water to a mix of customers, ranging from individual homeowners to municipal water utilities, privately managed water systems, and golf courses.

Driving this project were the characteristics of wholesale water meters. They tend to be hard to get to, underground in shallow or deep vaults, covered with heavy cast iron lids,

Lower Colorado RiverLake Austin, Austin, TX

and their meter registers are likely to be under water, mud or fogged over.

Reading LCRA’s 100 wholesale water meters may take almost a week of a meter reader’s time, including initial and re-reads. Under water, the numbers 3 and 8 look alike, and the readers face risks -- one meter sits at the end of a path bordered on one side by a thorny hedge and on the other, a pond full of water moccasins. Briefly, manual reading is time-consuming, unreliable, and risky.

First, we identified the meters where we wanted to test our ideas. Both measure potable water that LCRA treats and sells wholesale to water system management companies. And both serve subdivisions outside Austin. Second, neither meter is close to electric or telephone service, so we knew we’d need to be self-sufficient, with setups comprising a solar power source, a data logger, and a cell phone. Third, we had a new meter that would not require testing and calibration and an older one whose accuracy needed verification.

The next task was finding data logger, cell phone, and solar power equipment compatible with each other, reliable in unprotected environments, and adaptable to reading the meters’ pulse contactors. After a brief but intense search for services, we concluded that LCRA’s own weather and stream monitoring equipment -- our hydrological and meteorological or “Hydromet” infrastructure -- was the best bet for a pilot test. Our Hydromet group uses a data logger designed specifically for hydrology by a company named Sutron. It provides a kit including a data logger, a solar voltaic power panel, a power inverter, a battery,

21300 RIDGETOP CIRCLE STERLING, VA 20166 WWW.SUTRON.COM (703)406-2800 (703)406-2801 FAX SALES@SUTRON.COM

and a communication link in a NEMA enclosure. Even though the Sutron logger provides many more functions than we needed, we used it for convenience. And while our Hydromet network uses radio, we opted for a cell modem as the communication device.

The real challenge was enabling the Sutron logger and the Itron MV-90 data collection system to use the same language. Ultimately, we knew we wanted to be able to provide both register reads for billing purposes and intervals for planning and rate design. Interval data would provide load curves of water use.

We assigned meter channels for units of measure by function. Both sites use channel one to record battery voltage, a means of checking on the batteries’ charges, a suggestion from our Hydromet crew.

Flow and intervals were trickier. Each meter has two water lines with its meter and register: a smaller, main feed and a larger “fire line” for emergency needs.

Essentially, we had to write what Itron calls a translation interface module (TIM), which enables logger data to mesh with MV-90. Sutron’s software package XConnect interrogates communication devices and retrieves data from its loggers. This software has an export feature to transfer data to multiple interfaces.

We talked to Sutron and provided the DATA import format from an appendix of the MV90 documentation. With the proper export format, MV90 can import the XConnect files in a “.dat” file.

When importing the data type file, it uses the MV-90 master files as reference. We assigned meter channels in MV-90 to collect battery voltage, water flow, and, to produce a running use interval, a “DELTA.” DELTA is the difference between the current and previous 15-minute interval’s flow. We also elect the register read for each meter head. From those units of measure, then, we can see demand, a load curve, and the register reads for billing purposes.

Before installation, we tested each step -- data collection, unit of measure verification, and communication links. After the testing, we started collecting data reliably in November 2005. As with all remote metering, the weak link remains communication. Cell service cuts in and out, just as it does for remote reading of electric meters. We are testing the modem-logger connections, measuring cell strength at the meter sites, and trying to diagnose the weakness to stabilize service.

Bryan Sanders is a metering analyst at the LCRA in Austin, Texas. He is responsible for the collection and validation of interval meter data for its key account program. He is the lead technical support for the meter data management software and hardware infrastructure. Prior to working at LCRA, he served in the US Army and Department of Defense

as a communications and electronic specialist. He holds a B.S. in computer science from Coleman College, San Diego.

Tom Knutsen is an energy services consultant for the LCRA in Austin, Texas. He and three other coworkers share responsibility for the meter and communications infrastructure, data collection, and billing data delivery for key end-use consumers served by LCRA’s wholesale customers. His writings on interval data management have been published in Transmission and Distribution World and Electric Energy T&D. Before LCRA, he worked five years as a reporter for daily newspapers in Texas. He holds an A.B. in history from Yale University and a master’s in communication from The University of Texas at Austin.

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WHERE WATER & ELECTRICITY MEET: REMOTE WATER METER READING

“...wholesale water meters...hard to get to, underground in shallow or deep vaults, with heavy cast iron lids.”