Linda Benedict, Parish, Richard L. | 10/4/2005 10:52:44 PM
Most people in the Gulf Coast area understand the value of home generators to keep power in their homes when hurricanes strike. Further from the coast, home generators are useful when ice or snow knocks down power lines.
Generators are also useful for projects that require electric tools away from an electric outlet.
Although most people opt for small engine-driven generators, a generator that connects to a tractor power-take-off (PTO) offers some real advantages, according to Dr. Dick Parish, an engineer with the LSU AgCenter’s Hammond Research Station.
Parish says the advantages of a PTO generator include no additional engine to maintain and more kilowatt capacity for your money. And a PTO generator can sit unused for many months and still be ready to go assuming you use your tractor regularly.
"One horsepower equals 0.75 kilowatt (kW), so you can multiply your tractor’s PTO horsepower by 0.75 and get an idea of the maximum size generator your tractor can handle," Parish says.
"Because the generator is not 100 percent efficient, you will probably not be able to actually deliver quite that much power," he says. "On the other hand, you can always buy a generator that is rated a little too large for your tractor and just not connect up a full electric load."
If you do overload the equipment, PTO rpm will drop, causing the frequency of the current to drop and perhaps stalling the tractor.
"Depending on size of the tractor and generator, the system may or may not allow you to run the whole house," Parish says. "Typically, you will be able to run lights and appliances, but not an air conditioner or heat pump."
The engineer says it is absolutely essential that a generator is connected to a house in a safe and approved manner.
Most small engine-driven generators just have outlets so you can disconnect your appliances from the house circuit and connect them directly to the generator. While PTO generators may also have some outlets for extension cords, they typically have one big outlet for a large 240-volt plug that can be used to connect to the house service entrance.
"Never connect to a home service entrance without going through an approved double-pole, double-throw transfer switch," Parish warns.
"This switch will completely disconnect the home service entrance box from the utility’s power lines when the generator is connected and vice-versa," he adds. "This is essential to avoid your generator feeding current back into the utility line and risking killing a utility lineman who is repairing the line. It also prevents utility power feeding back into your generator when the line power is restored."
Parish says to consult your utility company, use only an approved transfer switch and have the installation approved by the utility company.
"People’s lives depend on it." he warns.
Parish recommends not running computers and other sophisticated electronic equipment from any generator since the power may not be stable or "clean" enough.
"Don’t take the chance of ruining your computer or other electronics," he says
Parish says maintenance on a PTO generator is pretty simple.
"Keep it sheltered and out of the weather, be sure the tires are aired up (unless it’s permanently mounted on a pad or mounted on a 3-point hitch), and grease any fittings on the power shaft or other drive components," he says.
New PTO generators can be expensive, Parish says. But they generally cost much less per kW than engine-powered generators.
"PTO generators are a little harder to find but still readily available from tractor dealers and some mail-order supply companies," he says.
"It is sometimes possible to buy a used PTO generator from a farmer for considerably less than the cost of an equivalent new one," he adds. "If the generator has been sheltered and cared for, it should function as well as a new one for backup purposes."
Whether new or used, generators are easier and less expensive to buy when the weather is good rather than when a storm hits and generators are in urgent demand.
"PTO generators can provide a lot of peace-of-mind," Parish says. "They are far less trouble than engine-driven generators – if you already have a tractor. They can offer you more kilowatts for your investment than an engine-driven generator."
For information on related engineering and storm recovery topics, visit the LSU AgCenter Web site at www.lsuagcenter.lsu.edu.