Machinery Matters: Generators come to the rescue when stormy weather brews

2012-11-15T14:45:00Z Machinery Matters: Generators come to the rescue when stormy weather brewsBy Ann Marie Edwards Iowa Farmer Today
November 15, 2012 2:45 pm  • 

Winter hasn’t reared its head, yet. However, recent storms in the Northeast remind us how important back-up power can be. The effects of winter storms on farms in Iowa and Missouri can involve a number of issues.

Ice, snow and wind can take power lines down and leave you, livestock or other property without power.

An emergency source of power is essential for any farm with mechanically ventilated production facilities, bulk milk-handling equipment, automated feeding systems, or facilities requiring constant and consistent heat or refrigeration.

There are many generator options available, from tractor PTO-powered and gas- and diesel-powered portable generators to permanently installed standby generators powered by propane or natural gas.

Picking the right generator involves knowing yourself and your needs as well as understanding generators.

A full-load generator system will handle the entire farmstead load. Automatic engine-powered full-load systems will begin to furnish power immediately, or up to 30 seconds after the power is off. Smaller and less expensive part-load systems may be enough to handle essential equipment during an emergency.

Power-take-off (PTO) generators are about half as costly as engine operated units. Under a part-load system, only the most-essential equipment is operated at one time. For most farms this would be adequate, provided the generator is sized to start the largest motor.

For example, on a dairy farm, the milk cooler or ventilation fan would need to be operated continuously, but the operation of the silo unloader and mechanical feeding system could be postponed until the milking chores are completed. PTO units can be mounted on a trailer.

Ken Hellevang, North Dakota State University Extension agricultural engineer, says, “Even a small, standby electric generator could prevent costly losses during a power failure.”

Choose a generator that provides the power at the same voltage and frequency as the power lines supply, Hellevang advises. Most power lines supply 120/240-volt, single-phase, 60-cycle alternating current to homes and farms.

To help farmers buy the proper size generator, they need to decide what they must keep running, such as a furnace or certain farm equipment, Hellevang says.

Motors typically require four times the power to start as they do to run. Estimate power requirements from equipment nameplates when possible.

As a guide, electric motors require approximately 4,000 watts of power to start and 1,000 watts of power to run for every horsepower of output.

A typical home operating a water pump, refrigerator, freezer, furnace blower (gas furnace) and a few lights will require about 5,000 watts of peak usage for starting and 2,000 watts for continuous operation.

Electrical equipment normally is plugged into a smaller generator.

Extension cords must be properly sized based on the electrical load and distance from the generator.

THE PROPER voltage might not be provided to a motor at the end of a very long extension cord, which will cause damage to the motor.

Do not connect the generator to a home or farm electrical system without a transfer switch that disconnects the farm or home from the power line and connects to the generator.

The wiring system must be isolated from the power lines using a double-throw transfer switch to prevent the generator from feeding electricity back into the power line. This protects linemen who may be working to restore your service.

Also, without a double-throw switch, the generator can be ruined because of overload.

It’s advised to follow the operators manual to properly provide electrical power.

Instructions might include to turn off or disconnect all electrical equipment, or start the unit and bring the generator up to proper speed.

The voltmeter will indicate when the generator is ready to carry the load.

Check the voltmeter frequently. If the voltage falls below 200 for 240-volt service or 100 for 120-volt service, reduce the load

on the generator by shutting off some electrical equipment.

Hellevang reminds us of some safety rules to follow as well.

“Do not operate a generator in an enclosed or partially enclosed space. Gasoline or diesel engines may produce deadly levels of carbon dioxide,” he says.

“Carbon dioxide can accumulate in a building even with a large door, such as an open garage door.”

Wind blowing into an attached garage can push the carbon dioxide into the house.

If a generator is operated in an enclosed building, the engine exhaust must be vented outdoors away from the building using engine exhaust ducting.

For added versatility, some common farm tools, such as many portable AC/DC welders, can also be used for emergency power.

THE JOHN Deere Compresserator consists of a combination motor/compressor/generator. It’s available in wheel or skid models with power ratings of 1,600 to 4,000 watts.

Buyers can pick from 8- and 30-gallon capacity tanks and single- or two-stage compressors as needed for particular applications.

John Deere also offers generator accessories such as lifting hooks, generator covers or wheel kits.

Copyright 2015 Iowa Farmer Today. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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