Summer 2024 | Edition 29
Understanding Line Loss
BY RANDY SCHMIDT, PRINCIPAL ENGINEER AND MANAGER OF ENGINEERING AND OPERATIONS
Electricity powers our lives, but before it can reach our homes and businesses, a portion of it is lost along the way. This phenomenon, known as line loss, occurs during the transmission and distribution of electricity through the grid, most often from conductors and transformers. So, what causes these losses, what's considered normal, and how can utilities tackle this challenge?
WHAT CAN CONTRIBUTE TO HIGHER LOSSES?
Several factors can contribute to higher percentages of line loss:
Conductors: Heavily loaded circuits and long circuits have higher losses. An economic conductor analysis can help determine the optimal conductor size for new or upgraded loads, reducing both losses and costs.
Underground Conductors: These have additional loss components due to the type of insulation used. For example, Ethylene Propylene Rubber (EPR) typically incurs higher losses than Cross-Linked Polyethylene (XLPE).
Transformers: These are the largest contributors to system losses. Transformers have two types of losses: No Load and Load. No Load losses occur when the transformer is energized constantly but not supplying a load. Load losses, which vary with the load, are much larger. Overloading a transformer significantly increases load losses. Proper transformer sizing is crucial; smaller transformers have lower No Load losses but can lead to higher overall losses if undersized for consistent loads.
WHAT IS A GOOD PERCENTAGE?
The U.S. Energy Information Administration (EIA) estimates that annual electricity transmission and distribution (T&D) losses averaged about 5% of the total electricity transmitted and distributed in the United States from 2018 through 2022. Other sources indicate the average distribution cooperative losses ranged from 5% to 6%. For electric cooperatives, substation losses usually range from 4% to 7%, with the overall system average falling close to 5%.
WHAT CAN CAUSE PERCENTAGE INACCURACIES?
System losses are typically calculated by comparing the kilowatt-hours (kWh) purchased to those sold. Inaccuracies often arise from human errors during data entry into the Customer Information System (CIS). Incorrect metering multipliers or CT/PT values can lead to incorrect kWh calculations, impacting both sales and loss figures. (Issues with meters or metering equipment can also contribute to inaccurate data, but are less frequent.)
ARE THERE TECHNIQUES TO REDUCE LINE LOSS?
Utilities can implement several techniques to decrease line loss, with varying degrees of success depending on the specific system. Key strategies include:
Balancing Load: Ensuring circuits are evenly loaded to reduce strain on individual phases.
Feeder Reconfiguration: Redistributing load among feeders to shorten transmission distances.
Voltage Optimization: Adjusting voltage levels to minimize energy dissipation.
Power Factor Correction: Using local Volt-Amp Reactive (VAR) support to reduce dependence on distant power sources.
Upsizing Conductors: Installing larger conductors.
Optimally-Sized Transformers: Using appropriately sized transformers for their load.
High-Efficiency Transformers: Implementing high-efficiency core transformers to improve system performance.
When implementing these techniques, it is crucial to weigh the costs against the potential benefits to achieve the most effective balance.
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About the Author: "Randy Schmidt, Principal Engineer and Manager of Engineering and Operations, has been a fixture at STAR Energy Services and a cornerstone of our engineering team for over 23 years. With 30 years of experience as an Electrical Engineer, Randy brings a wealth of knowledge and expertise to the field of electrical engineering." –Lois Croonquist
‘Intern’al Spotlight: Shining a Light on STAR’s Internship Program
FEATURING A Q&A WITH BRENDAN BUROS, ELECTRICAL ENGINEER AND FORMER INTERN
At STAR Energy Services, our internship program has been a springboard for countless aspiring electrical engineers, many of who call STAR their home. Brendan Buros, who recently transitioned from intern to full-time Electrical Engineer, embodies the success of our program. After spending three summers interning with us, Brendan's journey highlights the immersive experience our interns receive, experiencing all aspects of the utility industry, from the substation to the meter. His story is just one example of how our internship program fosters professional growth. Read below as Brendan shares his firsthand perspective on his internship journey, offering a glimpse into the opportunities and growth that define STAR's program.
HOW DID YOU LEARN ABOUT STAR’S INTERNSHIP AND WHAT INTERESTED YOU ABOUT IT?
At the end of my sophomore year in college, my father suggested I explore opportunities at STAR. After a series of interviews, I was convinced that STAR offered more valuable learning experiences than other internships. Choosing STAR was the right decision, as I gained extensive knowledge and skills during my three internships, which significantly contributed to my professional and personal growth.
WHAT WAS THE WORK ENVIRONMENT LIKE?
I found the work environment at STAR to be fun, calm, and easy-going. It is a fantastic place to learn about the power industry.
WHAT WAS THE MOST REWARDING PART?
One of the most rewarding parts of my internship experience was learning from an energetic team dedicated to teaching interns. They focused on creating well-rounded engineers through field trips to utilities and insightful conversations with industry professionals.
CAN YOU DESCRIBE THE ROLES AND RESPONSIBILITIES YOU HAD DURING YOUR INTERNSHIP?
During my first internship, I handled general tasks for the engineering team and learned about the electric distribution industry, including creating engineering models of distribution grids, gathering data, making archaeological survey maps, conducting soil resistivity testing, completing various tasks for engineers, and even helping perform underground cabinet inspections. In my second internship, my role stayed the same but my responsibilities expanded to generating engineering models, data gathering, and completing environmental reports. By my third internship, I was assisting new interns, completing Spill Prevention Control and Countermeasure Plans (SPCCs) for various locations, attending staking courses, touring a warehouse to learn about devices and equipment, participating in safety crew observations, conducting substation infrared scans, engaging in solar commissioning, shadowing employees at MiEnergy Cooperative, and visiting a coal plant. These experiences deepened my technical understanding of the industry’s operational dynamics.
WOULD YOU RECOMMEND THIS INTERNSHIP PROGRAM?
I highly recommend STAR’s internship program. When I first started, I didn't know a lot about the industry, but I was given so many opportunities to learn and gain a comprehensive understanding of how it works. This internship would be beneficial to anyone looking to enter this field.
WHAT ADVICE WOULD YOU OFFER TO FUTURE INTERNS?
My advice to future interns at STAR is to always ask questions. I learned that asking questions is crucial for understanding the proper steps and avoiding mistakes, and by seeking clarification, I was able to handle similar problems with ease.
It’s Time to Power Your Career!
Message from the CEO
BY: LOIS CROONQUIST, CEO
CELEBRATING STAR'S SAFETY EXCELLENCE ACHIEVEMENT
I am pleased to announce STAR Energy Services was awarded the 2023 Minnesota Governor's Diamond Safety Award by the Minnesota Safety Council. This significant achievement highlights our commitment to advocating and prioritizing safety and health in all that we do. It reflects the hard work and dedication of our entire team in upholding the highest safety standards in our industry. The Diamond designation signifies that our organization has achieved an incidence rate better than the 97th percentile of the state and national averages. And we are in great company; STAR supports the safety initiatives of five other utilities that received this prestigious award.
Congratulations to the STAR team!