I =

Amperes per phase

E =

Volts per phase

Z =

Impedance per phase

Eff =

Efficiency of hp output generating device

PF =

Power factor

In its simplest form, an electric generator consists of a loop of wire rotated in a magnetic field by an external force. As the loop rotates, an electromotive force (emf) is induced and, if an external circuit exists, a current is produced.

Most electric generation systems produce three-phase power by driving an alternating current (ac) generator with a prime mover. An ac generator, or alternator, as it is commonly referred to, is an electric machine that converts rotating mechanical energy into ac power.

There are two types of generators typically used for ac power production. Induction generators are used for parallel operation with an existing ac power source. Induction generators typically range in output from a few kW up to about 1,000 kW, though much larger capacity units do exist. The interconnection of the induction generator with the utility-derived power system is typically quite simple.

Synchronous generators are capable of operating independently. From the largest central utility generating station to the smallest emergency or standby power system, this is the most common type of generator in service today. Interconnection with another ac power source requires careful planning and design. Protection at the interconnection point consists of at least a synchronizing device to assure that the two sources are synchronized before they are connected together. After connection, controls and protective devices are required to assure continued safe operation for the equipment and the power system.

Following are descriptions of both types of generator, as well as descriptions of single-and three-phase power generation, generator selection, and control.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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