Common Questions About Diesel Generators

by Starlight Generator dieselgeneratortech

What is a Diesel Generator?

A diesel generator is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy. A diesel compression-ignition engine is designed to run on fuel oil, but some types are adapted for other liquid fuels or natural gas.

Diesel generators are used in places without connection to a mains electricity supply, or as an emergency power-supply if the grid fails.

How do Diesel Generators Work?

A diesel generator converts diesel fuel into electricity. The diesel engine burns diesel fuel in order to produce motion for the generator, which converts the motion into electricity by using electromagnets.

Though a number of fuels can be used to power similar engines, diesel is generally preferred for generators because of its ability to burn but not explode. The fuel tank of the diesel engine is filled, and the engine is started. A throttle and governor are used to keep the speed of the diesel engine consistent in order to control the power output of the generator while also preventing damage to components that could be caused by the engine operating at too high a speed.

As the diesel engine turns the crankshaft that connects to the generator, the central axle of the generator is spun within a chamber containing electromagnets. This high-speed motion causes an electric current to be produced, which is then available for use by any equipment that is plugged in to the diesel generator.

What is an Acoustic Enclosure?

Generators are large, noisy and potentially dangerous, so where they are sited and how they are protected demands special care. Acoustic enclosures protect the machinery and those who work with it from noise, vibration and the risk of fire. They also offer protection from the weather as well as provide security, safe access and ventilation.

Where can Diesel Generators be Used?

Portable Generators are usually used for residential purposes to power a few domestic appliances during a power failure or at construction sites that have no source of electrical power required to operate tools.

Commercial Standby / Industrial Generators are used in commercial facilities such as hospitals, offices, manufacturing plants, mining operations, nursing homes, emergency services and data centres. Anywhere that cannot risk its ability to function being discontinued, due to a power failure, usually has a generator in case of such circumstances.

What is a Diesel Engine?

The diesel engine is a type of internal combustion engine, a compression ignition engine. The fuel in a diesel engine is ignited by suddenly exposing it to the high temperature and pressure of a compressed gas containing oxygen (usually atmospheric air), rather than a separate source of ignition energy (such as a spark plug). This process is known as the diesel cycle after Rudolf Diesel, who invented it in 1892.

Types of Diesel Engines

There are two classes of diesel engines: two-stroke and four-stroke. Most diesel engines generally use the four-stroke cycle, with some larger engines operating on the two-stroke cycle.

What is the difference between kW and kVA?

kW – kilowatt

kVA – kilovolt – ampere

The main difference between these two measurements is the power factor. kW is real power, while kVA is apparent power (real power + reactive power). The power factor is typically 0.8, however it can range from 0 to 1. The kVA will value will always be higher than the kW because it includes the reactive power.

Other than the US and a small number of other countries who use kW, the rest of the world tend to use kVA as the primary value, when referring to generators.

The kW unit rating is the power output a generator can supply based on the horsepower of an engine. Horsepower is a unit of measure of power (the rate at which work is done) equal to 550 foot-pounds per second. This is equivalent to 745.7 watts.

For example 1 horsepower = 745.7 watts, therefore a 500 horsepower engine has a kW rating of 372,850.

What is a power factor?

The power factor (pf) is defined as the ratio between real power (kW) and apparent power (kVA).

0.8 (pf) x 1500kVA = 1200kW

The standard power factor for a three phase generator is 0.8. The pf found on the ID place of a generator relates the kVA to the kW rating. Bearing in mind that power factors are anything between 0 and 1, generators with a higher power factor are more efficient in transferring energy to the connected load, whereas generators with a lower power factor are not as efficient and result in increased power/fuel costs.