Electric System Upgrades Preserve Reliable Service

Transformers that change the voltage of electricity for safe delivery to homes and businesses are essential components of the electrical grid.

Each year, Tucson Electric Power replaces two or three substation transformers, upgrading and modernizing the system to ensure continued reliable power delivery for all customers.

“If you think of transmission lines like arteries, the transformer is equivalent to the heart,” said Ernesto Ojeda, Director of Equipment Construction & Maintenance for TEP’s Transmission and Distribution department.

Transformers come in several sizes and are located at various points along the grid. “Within TEP’s system, about 250 substation transformers are carefully monitored, assessed and ultimately are prioritized for replacement,” said Susan Gray, TEP’s Vice President for T&D Operations and Engineering.

When deciding which transformers to replace, TEP takes into account dozens of factors such as data from regular monitoring and annual maintenance and the importance of each transformer relative to the entire system.

“It’s just like a car. If you’re spending more and more on maintenance, then it’s time to consider replacement,” Gray said.

TEP doesn’t wait for an emergency. Instead, it strategically makes system upgrades, saving time and money while making the grid stronger.

“Transformers undergo an extensive battery of tests and review by our maintenance engineers,” Ojeda said. “We want to replace them proactively before they fail and cause a power outage.”

Larger substation transformers are expensive, costing about $3 million per unit. They are customized according to their function and location within the grid and take more than a year to construct. Once up and running, each transformer has a lifespan of 50 years or longer.

By investing prudently in essential equipment like transformers, TEP can maximize the life span of the grid’s components, minimizing costly emergency repairs and improving the overall reliability of the system.

“By strategically planning where we devote our resources, we contain our total costs and save our customers money,” said Cynthia Garcia, Director of Transmission & Distribution Project Delivery. “Our objective is to provide safe, reliable and affordable electric service for our customers. Proactively monitoring and replacing equipment helps us reach that goal.”

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