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Whitehead & Associates Helps Cumberland Electric Membership Corporation (CEMC) Convert Substation

Challenge

Whitehead & Associates completed a year-long project with the Cumberland Electric Membership Corporation (CEMC) in cooperation with Howard Industries to convert a two-sided substation to dual voltage. The existing operating voltage was 15kv (7200v) and with the upgrade, CEMC was endeavoring to convert to 25kv (14,400v). Because there was not enough land to create an entirely new station, Whitehead and the team worked together to upgrade an existing property to the new voltage.

Joel Morris, Supervisor of Substation Maintenance at CEMC, says the project was a significant one because of the challenge of having to shut down one side and then the other to complete the switch. “This was one of the CEMC substation 3hardest things we’ve ever had to do—putting the lines back and forth and changing the voltages. The complication of having one side hot and the other dead was challenging as well. Plus, we had to convert outside the substation. So, there were many moving parts to this project.”

Solution

To begin the switch, CEMC installed a dual voltage unit 15kv on one setting and 25kv on the other setting in the station. They built the dual voltage transformer at 15kv and then shifted the load off of one side so it could be torn down to build the new 25kv upgrade. Once the 25kv renovation was complete, they again shifted the load off of the unit. Once the load was on the new 25kv transformer, CEMC switched the dual voltage unit to 25kv.

Shawn Rohan, sales for Whitehead & Associates, says, “The beauty of having a DV transformer on their system is they automatically have a spare if any of the other substation transformers go bad at either voltage. So in a sense they got a two for one deal without a significant capital investment.”

“After everything had been upgraded both sides were ready to go, and we can now switch the load back and forth between the two units,” explained Morris.

Whitehead & Associates worked with Howard Industries to supply a 161KV to 25/15kv dual voltage transformer to complete the project. Howard Industries has been producing medium power substation transformers for the last 6 years out of their Ellisville, Mississippi facility. Their scope now goes up to 230kv, 60 MVA base at 900 kV BIL. They have several hundred units in operation across the country.

Rohan said the entire project took a year. “All-in the work probably took eight months of solid contractor work but with weather and construction delays we finished in just inside a year.”

“This was a huge undertaking and working with Whitehead and Howard Industries really helped us stay on task and get things done properly. They were knowledgeable and ready to help with the right products made to our specifications and ready when we needed them,” said Morris.

Morris also added that this is the second dual voltage station they have. “We had used one dual voltage before. Still serving the load at 15 now, we’ll transfer it over. This is the first one we’ve done where we had dual voltageCEMC substation 4 and then changed it. The other one we haven’t changed yet. Because of the success of this project we are confident in our ability to make these kinds of changes.”

About Cumberland Electric Membership Corporation

For 75 years, Cumberland Electric Membership Corporation (CEMC) has been a power distributor in a growing five-county area, serving Cheatham, Montgomery, Robertson, Stewart and Sumner counties in Tennessee. Its goal is to provide reliable electricity at reasonable rates. CEMC purchases electric power from the Tennessee Valley Authority (TVA) at wholesale rates and distributes it to CEMC members. Being a cooperative, CEMC is a not-for-profit organization governed by a board of directors elected by the membership.