EPRI, CenterPoint Identify Modifications to Improve Power Quality at Frito-Lay Facility
Production of delicious snacks is running much more smoothly thanks to an EPRI power quality assessment at Frito-Lay’s Rosenberg, Texas facility. In 2017, EPRI and utility CenterPoint Energy identified modifications in the facility and on the grid to enhance the plant’s power quality and significantly reduce production shutdowns.
Applying Decades of Power Quality Experience
Since the 1980s, EPRI’s Industrial Assessment team has conducted more than 300 power quality assessments in 11 industrial sectors worldwide. EPRI has power quality expertise both on the utility and facility side of the meter—a rare combination—and collaborates with utility and facility staff on assessments. EPRI’s recommendations often yield hundreds of thousands of dollars in annual savings.
“Power quality assessments are like solving puzzles,” said EPRI Principal Project Manager Mark Stephens. “We examine power quality data and equipment in a facility, find the weak links causing the shutdowns, and figure out the lowest cost solutions.”
Stephens reports that the most common problems involve devices such as sensitive AC relays and automation equipment that are susceptible to voltage sags in the power supply. When the voltage dips below a certain threshold, equipment and processes may shut down—often at significant cost to industrial facilities. Solutions often include deploying new devices that can continue operating during—or “ride through”—deeper and longer voltage sags.
Through more than three decades of research, laboratory testing, and industrial assessments, EPRI has collected extensive power quality data, such as equipment performance during voltage sags. During assessments, EPRI’s Power Quality Investigator software draws on this database to determine those devices most susceptible to interruptions along with potential solutions and their costs.
“What makes EPRI so skilled at these assessments is that our technical staff are applying decades of research,” said Stephens. “Unlike others who do this work, EPRI doesn’t come connected with any particular vendor or technology. We’re not trying to sell equipment, so we can be objective in our recommendations. We present solutions as a menu of options with different costs and paybacks, and we never recommend solutions that we haven’t tested thoroughly in our labs.”
The Assessment: Panels, Controls, and Equipment
Frito-Lay’s Rosenberg facility reached out to EPRI and CenterPoint to address voltage sags that caused production line shutdowns.
“Frito-Lay has a workforce of multi-trade technicians that perform equipment maintenance and troubleshooting,” said Chris Allison, a senior principal engineer at Frito-Lay. “The type and severity of the power quality issues at the Rosenberg facility were outside of their expertise. Outages not only cause waste in product and labor but also create conditions that require a great deal of care to protect the safety of the people and equipment in the plant. We needed an engineering study that could identify the root causes and recommend solutions to eliminate the outages.”
The EPRI team examined engineering drawings, facility power quality data, and shutdown logs and inspected production line equipment, electric panels, and wiring as well as support systems such as water chillers and compressed air. They identified programmable logic controllers, relays, and motor starters that are sensitive to voltage sags and recommended replacing them with inexpensive devices able to ride through sags. EPRI also found dead batteries in uninterruptible power supplies in equipment control panels, recommending battery-less protective devices.
“During assessments, we commonly find dead batteries in uninterruptible power supplies,” said Stephens. “These devices are often used in places that aren’t regularly maintained, and there are no alerts when the batteries die. We often recommend other devices that provide the same function—uninterrupted electric service through voltage sags—but that don’t need batteries.”
Stephens says that fixes at individual electric panels, machines, and control devices (where power is low voltage) are much less expensive than fixes at the level of the entire facility (where power is high voltage).
“Fixing machines and controls can cost hundreds or thousands of dollars while deploying technologies intended to protect the whole facility can cost millions of dollars,” he said.
Reconfiguring the Distribution Grid
EPRI estimated that its recommended modifications in the facility would address about two-thirds of the interruptions and that the remainder would require changes on the utility side of the meter.
As a part of a one-day “drive down” of the distribution grid supplying the facility, EPRI and CenterPoint staff examined nearby feeders and substations to assess how grid faults may contribute to voltage sags and power interruptions. EPRI also modeled the impacts of faults on the facility. CenterPoint and EPRI agreed that the best solution was to reconfigure several feeders in the area to reduce the facility’s exposure to faults.
“Faults on a distribution feeder can lead to voltage sags in facilities served by the feeder,” said Stephens. “They can also cause interruptions at sites served by adjacent feeders. The location of the Frito-Lay facility with respect to various feeders in the area exposed it to an unusually high number of faults. Reconfiguring the feeders to reduce fault exposure is much less expensive than deploying equipment that enables the facility to ride through the grid interruptions.”
“EPRI plays a valuable role in enhancing the utility-customer relationship. Through its power quality assessment at a large customer’s facility, EPRI’s affirmation of the utility work already completed or underway—as well as the specific identification of issues within the facility that the customer could address—resulted in several efficiencies and improvements,” said Scott Cryer, power quality manager at CenterPoint Energy.
Since the Rosenberg facility implemented EPRI’s recommendations and CenterPoint reconfigured the nearby grid, Frito-Lay estimates annual facility savings of about $100,000.
“The great thing about EPRI is they have a vast amount of experience in eliminating power quality issues on both the utility and the customer side,” said Frito-Lay’s Allison. “The trust in EPRI’s expertise helped all parties to jointly resolve these issues. The end result was an elimination of outages as a result of sags and other power quality issues. Even weather-related outages due to thunderstorms were eliminated by hardening the Frito-Lay systems and reconfiguring the utility distribution to the plant.”
Prior to the Rosenberg assessment, EPRI conducted power quality assessments at Frito-Lay facilities in Ohio, Virginia, Arkansas, California, Kansas, and Utah. An assessment is planned for a Frito-Lay facility in Orlando, Florida.
Key EPRI Technical Experts:
Mark Stephens
For more information, contact techexpert@eprijournal.com.
Photo of Frito-Lay production line courtesy of Frito-Lay
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