Generators for Work, Play, and Backup Power

While backup power in emergencies is vital, it's not the only 
reason to have a portable generator on hand. And when it's crucial to 
maintain consistent power during an outage, portables are not always the
 best answer. Generac Power Systems

Steve Maurer, IME

While backup power in emergencies is vital, it's not the only reason to have a portable generator on hand. And when it's crucial to maintain consistent power during an outage, portables are not always the best answer.

Power for work and play
There's nothing like having portable power for work and play. However, the requirements might be different for each. In fact, one of the first decisions to make is whether you need a conventional generator or an inverter generator.

What's the difference? After all, don't both supply 120-volt AC power?

Yes, both do. However, the way the power is generated is the biggest difference. In a generator, the engine powers a mechanical alternator at 3,600 RPM to produce the raw 120-volt AC power. It may even have 240-VAC capability.

An inverter, on the other hand, uses the engine and alternator to produce raw DC voltage, which is then converted electronically to AC voltage. So, what makes the difference... to you?

The conventional generator is the workhorse of the two. It can supply adequate electricity to power tools and other equipment, great for the one-man contractor or DIYer to a full work crew, depending on wattage capability. They run on either gasoline or diesel fuel. Some models are capable of using LP gas.

It runs full-bore at 3,600 RPM to supply a constant flow of energy. The power may fluctuate depending on the load. This "dirty" power is not suitable for electronics in most cases.

The inverter model, however, is smaller and generates a lower wattage supply. Adequate for around the home, hobby shop or tailgate parties, the power supplied is "cleaner," meaning few if any spikes and brownouts. That makes it a better choice for powering electronic devices, such as computers, TVs and DVRs, and some small appliances. They are normally designed for gasoline consumption.

Fuel consumption is another difference. As mentioned, the conventional generator roars along at a constant 3,600 RPM. The inverter generator, however, varies the speed of the engine in relation to the load required. If the load drops, the speed is reduced. This makes it more energy efficient. That's one reason they work good for camping and tailgating. The energy requirement is low, allowing a small tank of fuel to last a long time.

If you're not sure what you need, many manufactures have charts and calculators to help you decide.

Generators for backup power
Here again, you have a wide selection. Many homeowners opt for using a portable conventional generator to supply emergency power. Since it can be used for other purposes, this often makes sense. Even so, remember that the power supplied is limited, again depending on the size of the generator and the circuit requirements.

Most portable can supply between 6 and 16 circuits. That said, when motor-driven devices — like refrigerators and furnaces — start up, they draw more power at the inrush and may use more power than planned for. That means that some circuits may need shut off during that time. Inconvenient, sure. But remember… this is emergency power, not an extended run.

Another option is a permanently installed, hard-wired generator. These are designed to run either pre-selected circuits or even whole house power. They start automatically during a power failure and shut off when line power is restored.

Whether you use a portable generator or a permanent installation, a transfer switch is required. This keeps your generated power from backfeeding into the utility lines. Backfed power is dangerous to power company employees working to restore service. It can also run in on neighboring homes, causing damage or injury.

A quick word about backup power for commercial and industrial settings. Obviously, the requirements are more demanding, so portables just aren't feasible. Larger generators automatically restore power to these buildings, often within microseconds. Diverse types of businesses and services have individual needs, and often are governed by regulatory standards. The generator used must be matched to the required codes.

Additionally, many businesses outgrow their original emergency generators. This can mean replacing the old installation. However, some generator manufacturers have systems that can be expanded as necessary. That's worth checking into when designing and purchasing an emergency backup power system.

On a final note, larger portable generators are also available for rental. Two reasons for rentals are temporary power for events such as carnivals or outdoor meetings, and quick emergency power when a permanent generator is not on premises.

Photo courtesy of Generac Power Systems

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