Looking for a simple way to reduce cost of operation?  Have you viewed your energy bill, lately?

The cost of energy has been skyrocketing.  Water and wastewater utilities are becoming aware of the large cost of energy bills as part of their bottom line.  Much of the cost of energy at these utilities is directly related to electric motors.

Energy audit at pumping station in Mequon, Wis.

Here are statistics from the Department of Energy (DOE):

• Nearly 25% of all of the nation’s electricity demand comes from industrial motor systems
• Over 50% of pump “life-cycle-costs” result from energy and maintenance expense
• Less than 15% of pump “life-cycle-costs” are initial purchase costs
• Energy savings of 20% or more are possible with systems optimization

In addition, power and efficiency levels are defined – allowing comparison to published data for the pumps as installed.  It’s like having the DNA for pump/motor combinations in actual field conditions.  And, the data is now available for comparison to future measured values – tracking performance in a scientific approach to optimizing performance.

In addition to awareness of power consumption, operators/owners of utilities need to be aware of the quality of the power they are buying.  Quality of electric power includes variation in power across the legs of three phase lines and variation in the quantity of variability in the sine wave being provided (sometimes containing harmonic variations).  The consumer of electric power rarely knows the quality of power being purchased at his metered location.  The quality of power being provided will directly affect the life span and operating characteristics of machinery being operated in the consumer’s plant.

Fortunately, there are simple instruments which a consumer of electricity can use to make quality and quantity checks for the power being purchased. I recently had the opportunity to borrow a “power pad” by Rockwell Automation/Allen Bradley in conjunction with a pump station audit for the City of Mequon, WI. PowerPad offers a wide assortment of measurement parameters in one compact device. It can determine both quality and quantity of power being provided to the end user and provides both qualitative and quantitative metrics to offer ways to improve upon the effective use of power while minimizing consumption by measuring and reporting. A photo of a typical field set up – with laptop, PowerPad and whiteboard at Mequon is depicted in the photo at left.

City of Mequon, Wis. Pioneers in Defining Pumping Station Performance Metrics

Actual recording of energy consumption for one pump cycle at Mequon, WI

The city of Mequon, WI – home of Allen Bradley’s Drives and systems division – elected to be pro-active in their defining the metrics of performance for their 21 wastewater pumping stations.  As part of their “metrics” project, they asked their consultant to provide energy consumption values for the pumps at their main pumping stations.  The Rockwell PowerPad portable power monitor was the perfect solution to their needs.  Each pump was run at design flow conditions and power curves were produced (an example of power/watts vs time for one pump cycle is shown in the graph) which defined energy consumption for the design conditions.

Thanks to Sean Schmelzer, P.E., Rockwell Automation, Allen Bradley Division for providing the PowerPad for this study at no cost.

Fred Schneeberg, Mequon Utilities Superintendent, for helping us through our first official pump station audit.

David Rice, Electrical Engineer, Port Washington, Wis. for sorting through the hardware and software to refine the field data.

Take care,
Don

Don Voigt, P.E.
Systems Engineer