How Does a Generator Create Electricity?
Article on How Generators Work (Page 2)

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Using Generators to Power Residential & Industrial Applications
While the underlying principle of operation to generate electricity remains more or less the same in all kinds of generators, the mechanism of powering up your application using the generator’s electrical output varies a little from one system to the other.

Portable Generators
These are usually used for residential purposes to power a few domestic appliances during an outage or at construction sites that have no source of electrical power required to operate tools like drills, saws and paint sprayers. You would usually require systems that generate at least 4 kilowatts (kW) of power.

Use of Extension Cords:
One of the most economical ways to ensure power supply during an outage is to use extension cords to directly connect a portable generator to power the chosen appliances in your home. 

Use of Power Transfer Switch:
A safer way to use a portable generator is to have a power transfer switch installed and connected to the main electrical panel of your house. As the name implies, a power transfer switch enables switching from a primary power source, usually the utility power, to a secondary or tertiary power source such as the generator when supply from the primary source is interrupted. Manual switches are operated through direct manipulation or by using a remotely wired control device. During a power outage, the transfer switch isolates the electrical panel from utility supply and connects it to the generator.

The generator can then be connected to the power transfer switch through an extension cord. Electrical output from the generator can then be fed into circuits through the main circuit breaker and used to power the required circuits. Critical and non-critical circuits of the panel can be grouped individually and separately wired such that the portable generator powers only the critical section as required.

Isolating the utility lines from the generator source also eliminates the risk of ‘back feed’. Back feed is the flow of electrical power from the generator into the utility lines, which can be fatal to electricians working on utility lines during an outage.

Residential Standby Generators
A portable generator is limited in utility since it can power only a few appliances. An emergency residential standby system can be used to deliver power for the entire household and can even keep air conditioners operational during a power outage. You can also choose smaller standby units to power only a few circuits to keep essential appliances like refrigerators, lights and fans running during an outage. These units typically range in power generation capacity from 6 kW to 40 kW.

Use of Automatic Transfer Switch
Standby generators are usually installed outside the home and are connected to the main electrical panel through an automatic transfer switch. The system automatically restores power to the household within about 20 seconds of a power failure without any manual intervention.

Commercial Standby / Industrial Generators
Industrial generators are used in commercial facilities such as corporate offices, manufacturing plants, mining operations, nursing homes, data centers, hospitals and so forth that simply cannot afford the risk of discontinuity in business operations during a power failure. These are often stationary units that produce anywhere from 50 kW up to 2000 kW of power.  Most smaller and residential generators are single-phase (120 Volts), but commercial generators are almost always three-phase (120, 240 or 480 Volts).


Use of Automatic Transfer Switch
Similar to residential standby systems, commercial standby / industrial generators are wired to the main electrical panel of the building through an automatic transfer switch and are fired automatically during a power outage. These are specially designed such that switching between the primary and secondary sources of power takes only about a fraction of a second and practically allows for seamless supply of power.

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