They’re not electric vehicles, but they do get up and go, plugging into the grid when needed.

Mobile substations play a crucial role in keeping the lights on for UniSource customers, often in fast-growing areas with increasing energy needs. In addition to supporting reliability while permanent facilities are developed, these portable facilities also help us restore service and reduce outage times during emergencies.

Substations adjust voltage to appropriate levels and provide other support for our local energy grid. UniSource has about 45 permanent substations throughout our service territory. Typically, it takes about five years to design, permit and build a permanent distribution substation. New transformers for those facilities can cost nearly $1.5 million each and take up to two years to build and install.

Mobile substations and skid-mounted transformers provide temporary solutions during periods of high energy usage, unexpected outages or ongoing upgrades to existing equipment. Once our permanent facilities are installed or repaired, mobile substations hit the road again to plug into the grid in another location.

“Mobile substations are designed to be reliable but flexible,” said Ernesto Ojeda, Director of Equipment & Asset Management. “They allow us to continue serving customers while we’re working on improvements to our energy grid.”

Today, a mobile substation is supporting reliability in the Meadview area north of Kingman, where customers’ energy needs have increased significantly in the last few years. To help alleviate voltage concerns and serve customers’ higher summertime energy needs, UniSource installed a mobile substation near Pierce Ferry and Antares Road in 2021. We also deployed generators and installed line conditioning equipment including capacitors and voltage regulators to support voltage for residential water well pumps in the area.

UniSource is building a new 10-mile 69-kilovolt (kV) transmission line from the Dolan Springs Substation on Pierce Ferry Road to the new Meadview Substation. Construction of the new substation, near Pierce Ferry and Smoketree Avenue, is expected to be completed early next year. The mobile substation will remain in place until new facilities are in operation.

UniSource also installed a temporary transformer last year next to the Sonoita Substation in Rio Rico to reduce strain on overloaded circuits used to serve residential and business customers. The mobile substation will help avoid overload conditions on local circuits until a new permanent substation is installed in the area.

UniSource recently invested about $3 million to purchase a new mobile substation for use throughout its service area. UniSource crews will inspect and perform maintenance on mobile substations and transformers in between deployments to ensure each piece of equipment is ready for emergency use.

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