One of the most popular ways to cool liquids is using metal fins and tubes in which a solution of water and glycol circulates – like an automobile radiator – augmented with fans. Another method is to have a radiator circulating oil through metal plates in a closed loop, like an oil-filled space heater. As energy costs rise, electricity generating companies are examining the cost of their systems that cool their electrical transformers reliably and looking for alternatives.
Transformers step up or step down voltage at electrical stations and require effective cooling to do it efficiently. One class of products that has been doing that for 80 years is offered worldwide by Trantech Radiator Products Inc. Depending on the system, when space is available, radiator panels can replace fan-cooled fin-and-tube systems.
“The better our radiators cool the oil and hold the temperature of the transformer, the longer the transformer will last,” President Greg Horton maintains. “For example, if you have a transformer at 100 percent capacity and it stays heated, the life of the transformer will be much shorter than that of one that is operating at a lower temperature.”
The company’s patent-pending E4 product uses a special design that requires fewer plates to produce the same amount of cooling as previous systems with more plates. That design reduces the cost of the radiator system substantially.
“We’re able to offer a plate design with a pattern that creates an avenue to hold more oil in it,” Operations Manager Kevin Riley explains. “It dissipates the heat through the more reliable natural heat-convection process rather than using parasitic power for oil pumps or fans for forced air circulation.”
Some customers have Trantech Radiator Products Inc. design their radiator system. “Sometimes we do the design work for the transformer companies or retrofit transformers to improve cooling based on data they provide us regarding heat dissipation,” Horton says. “We design that depending on what the customer wants. If they don’t want to have fans and worry about preventive maintenance on fans, we can design the cooling package with a radiator to keep the oil under a certain temperature range that the customer specifies.”
Because more plates require more space, some customers might want to reduce the number of plates by using fans. “It depends on what the customer is looking for and the envelope the customer has to work within,” Horton points out.
Besides the radiator’s design, its materials also can save customers money. “The other piece of cost savings that our customer looks for from us is we use primarily steel – whether it’s carbon or stainless – as our base raw material,” Riley points out. “When you get into forced-air, fin-and-tube cooling systems on transformers, your utility or the end-user is having to purchase tubes made out of copper and aluminum that are more expensive materials. The aluminum breaks down faster than the steel, and the copper as well. In the life of a transformer, you might replace three other types of cooling assemblies by the time you replace one of our radiators.”
Trantech is a radiator specialist, Horton emphasizes. “We sell to the companies that make the transformers.” All the company’s products are manufactured in its 138,000-square-foot plant in Edgefield, S.C. Among the manufacturing processes performed in the plant on its primarily steel products are roll-forming, punching, trimming, welding and painting.
The biggest manufacturing improvement in the company’s history was installation of an automated seam welder that uses resistance welding with direct rather than alternating electric current, Riley says. “Most seam welding applications in most businesses have not changed since the early 1970s,” he maintains. “There are some similarities, but it’s a totally different approach to seam welding. An in-line plasma welding application also improves the quality of our plates within our radiators. At the same time, we improved the quality of our paint coverage because of our plasma weld application. It gives us more control for each weld and more feedback for each weld to produce a higher quality product.”
The robotic welder travels alongside the steel as it comes down the conveyor line off a massive coil and welds the seam to create a plate. “The coil steel comes off the line as a plate,” Riley notes. The system has been operating for nearly two years. “It took six to eight months to actually get to the point of producing the product with the quality and timeframe that we wanted,” Horton remembers. A combination of outside vendors and in-house engineers worked on automating the process.
Take a Powder
Trantech radiators are painted on the inside and outside after welding. They are filled with an epoxy-based primer, then drained and the exterior is sprayed with a powder coating that is attracted electrostatically to the part because of its charge. Both coatings are then cured in a drying oven at the same time.
“Our powder coating system is state-of-the-art,” Riley maintains. “It’s the largest one in the U.S. is what we’ve been told by our equipment supplier. They occasionally bring potential customers to see our system. It’s not one they can have on the floor at their location. Some of our radiators are 190 inches long – the size of a car – and weigh as much as a car. So this system can handle something that big – it’s huge.”
The radiators also are leak-tested using several methods. One method is to pressurize the radiator with air, immerse it in water and then inspect it visually for air bubbles. Another method is to fill a radiator with a mixture of 5 percent hydrogen and 95 percent nitrogen and use hydrogen detectors to “sniff” for a leak.
Finally, a radiator can be filled with the oil it uses and run under a simulated load, which is done to test new or current designs. “Anything the customer may wish to do, we can simulate and test it as if it were in operation,” Riley maintains.
Efforts to improve the automated welding system’s operation along with the other processes in the plant are continual. “We’re working on process flow, value stream mapping and all those things,” says Riley, who joined the company in November 2011. “We’re implementing them a step at a time, not doing everything at once. The bigger thing about doing improvement is to have the culture change to take hold of it so it’s permanent. We’re still at the beginning phases of that. We’re on that road right now. We’re ahead of where we planned to be at this point in time. The plant has really taken off at full speed ahead and they’re doing great.”
The company is developing opportunities in the wind, solar and smart electric grid markets. Transformers step down high voltages of electricity from rapidly spinning wind turbines to a voltage that can be sent over power transmission lines. They also can store low, steady voltage such as from a hydroelectric dam until it builds up to a voltage high enough to be transmitted over the grid. In these applications and others, the transformers have to be cooled, which is the specialty of Trantech Radiator Products Inc.
Trantech Radiator Products Inc. was founded in 1932 in Lansing, Mich., and was relocated to occupy 126,000 square feet of manufacturing space in historical Edgefield, S.C., in 1970. It is ISO 9001-registered.
“The power grid is aging,” Horton maintains. “There are transformers still in operation beyond the normal expected life of a transformer. They have to be replaced, which helps us. Trantech’s forte is our ability to custom-make our radiators to suit our customers’ needs. The powder coating process leads to a better, long-lasting product. This is our 80th anniversary year, a celebration for the company. We plan to be here 80-plus more years.”