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Guides Buying a Generator

What is a Generator and how do I choose one ?

Generator is a machine that generates electricity. The two main components of the generator are the engine which supplies power and the alternator that turns power into electricity. There are two basic designs for generators - standby and portable generators.

The standby generators, generates from 5 kW to several hundred kW and are hardwired to the electrical system. The standby generators should have some safety features as an automated shutdown in case of low oil pressure, overheat, or overload. Most standby generators also have enclosures with noise reduction features, and should fit emissions regulations.

Portable generators provide power in places where the main grid is not available, locations as construction sites, mines and camping areas. Portable generators are smaller and cheaper but they can provide less power - from less than 1 kW to 15 kW, although "towable" generators can provide 200 kW or more.

There are several more differences between the different types of generators. Generators can run on natural gas, gasoline, propane or diesel which is used in larger, commercial generators. Generators can operate at one of two speeds: the quieter more resilient 1500 RPM or the smaller and lighter 3600 RPM. Another difference is in the generator's cooling system which prevents them from overheating. Air-cooled generators usually cost less but produce more noise. Liquid-cooled generators are quieter, more dependable, and much more effective. Liquid-cooled generators typically cost more than air-cooled.

Generators' electricity is measured in voltage and watts, it is important to determine your needs before choosing your generator. Voltage measures the "pressure" of an electric current (usually 120/240v) and Wattage measures the "volume" of electricity created. Wattage requirements increase with each appliance or equipment plugged in. The Wattage range can go anywhere between 1,000 watts (or a 1kW) to more than 2,000 kW. Residential operations usually need around 20-30 kW.

In order to estimate your needs create a list of all the equipment that needs to be operated by the generator during a power outage, from light bulbs to your air-conditioner. The recommended way to do this estimation is ask an electrician to measure your wattage with an ammeter. If you do the estimation yourself, please remember that electric motors use more power to start than they do to run so you'll need a capacity around 20% higher than your requirements. When choosing a generator, make sure to compare the 'rated capacity' - the level of power a generator can deliver on an ongoing basis.

Please check our average wattage requirement guide for more information.

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