Golden Service

Variable Speed Drive uses only needed water pressure

Published in the July 2009 Issue Published online: Jul 05, 2009 Tyler J. Baum, Photos by Steve Smede
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Byron Jensen and Brad Jensen of B&B Farms in Rexburg, Idaho, aren't worried about maintaining the right irrigation pressure on two of their pump systems.

They have two Variable Speed Drive (VSD) systems operating pivots connecting to that system, from Golden West Irrigation and Equipment in Rexburg, Idaho. If one of their pivots shuts off, they're not scrambling to relieve the pressure.

The VSD system will do it for them.

Today, water conservation-which translates into cost savings-is critical. Growers can't afford to waste water, nor can they afford to run more pressure than the irrigation system can handle. Any time an operation can cut back by only using the water they need-no more, no less-they're hitting pay dirt.

Golden West is helping growers do just that with their VSD system, and with much success.

The VSD panel is a system where the speed of the motor is regulated based on the amount of water that is being pumped. On systems where there are more than one pivot to a pump, one pivot shutting down won't increase the pressure-the VSD will slow the motor down to maintain the right amount of pressure to run the remaining circles. Growers who have to spill water in order to relieve pressure will no longer need to waste than precious resource, if they have a VSD.

Ben Jensen, the drive specialist for Golden West, is the man responsible for bringing the concept to Golden West. Ben started with the company in 1986, straight out of high school, assembling wheel lines. After leaving to earn his electrical license, he returned and is now in his 15th year with the company.

Ben says that before the drive system, if a pivot shut down at night it would high-pressure the whole farm so that there would be down time on the rest of the pivots, wasting precious irrigation time. Now, if a pivot shuts down the system will compensate by slowing down to maintain the same pressure.

There's also the convenience. If a grower wants to work on one center pivot, he only needs to shut down that pivot, not the pump with the rest of the running pivots.

"If you turn a circle on, the water is there. If you turn it off, it goes away," he says. "It also saves you on shock to your mainline system, where you maintain a set pressure instead of getting high-pressure spikes and damaging your mainline."


In 1966, Sylvan Seely started selling hand lines with little more than a handwritten price sheet and a Rambler to haul them. He decided it was time to try something other than farming in lava rock.

Sylvan diligently sold irrigation equipment while his wife, Gail, was milking cows and planting potatoes. Their eight children all spent time working in the family business as well, and Sylvan was able to add pumps and Thunderbird wheel lines to his product list.

It didn't take long, however, for Sylvan to realize that center pivots were the future of irrigation.

After incorporating his growing business under the name Gem State Irrigation, he built a shop in Rexburg and started investigating pivots. By 1969 Gem State became a Valley dealer, and has been one ever since.

In 1976, after Rexburg was flooded when the Teton Dam burst, the company temporarily re-located to Sylvan's garage and helped with the cleanup effort, as well as installing pumps in area canals to pump water back to local farms.

In 1988, during the Yellowstone National Park fires, Gem State-by then Golden West Irrigation-contributed portable pumps, mainline and expertise to protect the endangered community of West Yellowstone, Mont.

Golden West Irrigation and Equipment has now been in business for 42 years. Today, their services expand from Grace to Ashton, and from Howe to Driggs, with about 70 percent of the market share for pivots in that range.


According to Ben Jensen, the VSD system has been out for quite awhile, but Ben, much like Sylvan when it came to center pivots, saw VSDs as something that Golden West needed to be a part of.

"We didn't want to be on the sidelines of it," he says. "I went to Nick (Ricks, Rexburg general manager) and I said, `We want to do this. I want to do this, and I want you to help.'"

The system didn't come without a learning curve, however. Golden West has been installing drives for about five or six years, protecting the drive system in buildings. After many systems were installed, they realized that the electronics couldn't handle the harsh environment of the field-especially heat and dust.

Golden West applied for an Underwriters Laboratories listing so that they could come up with an appropriate solution. Now UL-listed as a 508A panel shop, Golden West installs the VSDs in air-conditioned, climate-controlled enclosures, which keep out dust and maintains a relatively cool temperature.

"They produce a lot of heat doing what they're doing," Ben says.

They also discovered a harmonic interference that goes back into the grid. The harmonics are created from the process of the voltage conversion in the drive.

"The [transistors are] switching that 720 amps many times a second to create a sine wave that allows the motor to run the speed we want it to. And that switching is what's actually creating the harmonics back into the power company."

To solve that issue, harmonic filtering has been incorporated into the enclosures.

"It's not putting the interference back into the power company-into the grid-[which] can affect everyone that uses power. It allows them to be more efficient in using power."

Golden West installs the systems for a wide range of horsepower-from 40-hp all the way up to 700-hp. They're seeing plenty of success with these VSDs, and it shows because they're installing about 25-30 of these systems a year.

"It's been good so far," Ben says. "I think the customers who have them are very happy. It's one of those things that once you have them, it's hard to do without."

That's certainly true as far as Byron Jensen of B&B Farms is concerned.

"It's the best money we've ever spent," Byron says. "It's quite a savings. It makes up for a lot of wasted water. You can run what you need to run, when you need to run it."

This is the second season that B&B Farms has used the two 600-hp VSD panels they had installed at the same time, and Byron isn't just impressed with the technology-the workmanship and service that Golden West puts into their products is "first class."

"Ben Jensen is very meticulous. He doesn't leave until the job is done."

The National Resources Conservation Service is even subsidizing growers for installing these systems, as is utility companies such as Idaho Power, Rocky Mountain Power and Fall River Electric.

Byron says it's well worth it.

"We don't know how we got by without them," Byron says.