Generators 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 ‘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.

The main components of an electric generator can be broadly classified as follows (refer to illustration above):

(1)Engine
(2)Alternator
(3)FuelSystem
(4)Voltage Regulator
(5)Cooling and Exhaust Systems
(6)Lubrication System
(7)BatteryCharger
(8)ControlPanel
(9) Main Assembly / Frame
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.

Battery Charger
The start function of a generator is battery-operated. The battery charger keeps the generator battery charged by supplying it with a precise ‘float’ voltage. If the float voltage is very low, the battery will remain undercharged. If the float voltage is very high, it will shorten the life of the battery. Battery chargers are usually made of stainless steel to prevent corrosion. They are also fully automatic and do not require any adjustments to be made or any settings to be changed. The DC output voltage of the battery charger is set at 2.33 Volts per cell, which is the precise float voltage for lead acid batteries. The battery charger has an isolated DC voltage output that does interfere with the normal functioning of the generator.

Control Panel
This is the user interface of the generator and contains provisions for electrical outlets and controls. The following article provides further details regarding the generator control panel. Different manufacturers have varied features to offer in the control panels of their units. Some of these are mentioned below.

(a) Electric start and shut-down – Auto start control panels automatically start your generator during a power outage, monitor the generator while in operation, and automatically shut down the unit when no longer required.

(b) Engine gauges – Different gauges indicate important parameters such as oil pressure, temperature of coolant, battery voltage, engine rotation speed, and duration of operation. Constant measurement and monitoring of these parameters enables built-in shut down of the generator when any of these cross their respective threshold levels.

(c) Generator gauges – The control panel also has meters for the measurement of output current and voltage, and operating frequency.

(d) Other controls – Phase selector switch, frequency switch, and engine control switch (manual mode, auto mode) among others.

Main Assembly / Frame
All generators, portable or stationary, have customized housings that provide a structural base support. The frame also allows for the generated to be earthed for safety.