Electricity
Electricity
Electricity
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What Anda How it Works electricity generator
electricity generator
Generator are useful appliances that supply electrical power during a power outage and prevent discontinuity of daily activities or disruption of business operations. Generators are available in different electrical and physical configurations for use in different applications. In the following sections, we will look at how a generator functions, the main components of a generator, and how a generator operates as a secondary source of electrical power in residential and industrial applications.
How does a generator work?

An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output.
It is important to understand that a generator does not actually ‘create’ electrical energy. Instead, it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. This mechanism can be understood by considering the generator to be analogous to a water pump, which causes the flow of water but does not actually
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‘create’ the water flowing through it.
The modern-day generator works on the principle of electromagnetic induction discovered by Michael Faraday in 1831-32. Faraday discovered that the above flow of electric charges could be induced by moving an electrical conductor, such as a wire that contains electric charges, in a magnetic field. This movement creates a voltage difference between the two ends of the wire or electrical conductor, which in turn causes the electric charges to flow, thus generating electric current.

Main components of a generator

The main components of an electric generator can be broadly classified as follows (refer to illustration above):
(1) Engine
(2) Alternator
(3) Fuel System
(4) Voltage Regulator
(5) Cooling and Exhaust Systems
(6) Lubrication System
(7) Battery Charger
(8) Control Panel
(9) Main Assembly / Frame
A description of the main components of a generator is given below.
(1) Engine
The engine is the source of the input mechanical energy to the generator. The size of the engine is directly proportional to the maximum power output the generator can supply. There are several factors that you need to keep in mind while assessing the engine of your generator. The manufacturer of the engine should be consulted to obtain full engine operation specifications and maintenance schedules.
(a) Type of Fuel Used – Generator engines operate on a variety of fuels such as diesel, gasoline, propane (in liquefied or gaseous form), or natural gas. Smaller engines usually operate on gasoline while larger engines run on diesel, liquid propane, propane gas, or natural gas. Certain engines can also operate on a dual feed of both diesel and gas in a bi-fuel operation mode.

(b) Overhead Valve (OHV) Engines versus non-OHV Engines – OHV engines differ from other engines in that the intake and exhaust valves of the engine are located in the head of the engine’s cylinder as opposed to being mounted on the engine block. OHV engines have several advantages over other engines such as:
• Compact design
• Simpler operation mechanism
• Durability
• User-friendly in operations
• Low noise during operations
• Low emission levels
However, OHV-engines are also more expensive than other engines.

(c) Cast Iron Sleeve (CIS) in Engine Cylinder – The CIS is a lining in the cylinder of the engine. It reduces wear and tear, and ensures durability of the engine. Most OHV-engines are equipped with CIS but it is essential to check for this feature in the engine of a generator. The CIS is not an expensive feature but it plays an important role in engine durability especially if you need to use your generator often or for long durations.

(2) Alternator
The alternator, also known as the ‘genhead’, is the part of the generator that produces the electrical output from the mechanical input supplied by the engine. It contains an assembly of stationary and moving parts encased in a housing. The components work together to cause relative movement between the magnetic and electric fields, which in turn generates electricity.

(a) Stator – This is the stationary component. It contains a set of electrical conductors wound in coils over an iron core.

(b) Rotor / Armature – This is the moving component that produces a rotating magnetic field in any one of the following three ways:
(i) By induction – These are known as brushless alternators and are usually used in large   generators.
(ii) By permanent magnets – This is common in small alternator units.
(iii) By using an exciter – An exciter is a small source of direct current (DC) that energizes the rotor through an assembly of conducting slip rings and brushes.
The rotor generates a moving magnetic field around the stator, which induces a voltage difference between the windings of the stator. This produces the alternating current (AC) output of the generator.
The following are the factors that you need to keep in mind while assessing the alternator of a generator:
(a) Metal versus Plastic Housing – An all-metal design ensures durability of the alternator. Plastic housings get deformed with time and cause the moving parts of the alternator to be exposed. This increases wear and tear and more importantly, is hazardous to the user.

(b) Ball Bearings versus Needle Bearings – Ball bearings are preferred and last longer.

(c) Brushless Design – An alternator that does not use brushes requires less maintenance and also produces cleaner power.