DIESEL GENERATOR- An Industrial Overview

DIESEL GENERATOR- An Industrial Overview

The journey of diesel generator was started in early 1890s by Rudolf diesel. Also diesel generator gets its name from its inventor  but that ignition-combustion engine was very slow in speed because of its limitations but with the innovation it gets improved.

Basically diesel engine  are divided into two types, One is two stroke engine and other one is four stroke engine. In two stroke engine one is compression stroke and other one is power stroke. But in four stroke there are four steps first is intake then compression then power and at last there is a exhaust stroke.


The diesel generator consists of many parts. The major parts of diesel generator are:

  • Engine
  • Alternator
  • HMI
  • Filters
  • Turbo 
  • Radiator. 


Basically main purpose of engine is to change the any form of energy into mechanical energy. There are two types of engine, One is two stroke engine and other one is four stroke engine.

Mainly in diesel generator four stroke engine is used. The Four stroke are:

1. Intake

In the piston box, there are two valves, inlet valve and outlet valves. During first step inlet valves are open and outlet valves are closed and  fuel(diesel) and fresh air  is enter in the piston box through the inlet valve and piston goes down.

2. Compression

In compression stroke, Piston compress the fuel and air in the cylinder. The amount of the fuel is 20 percent and rest 80 percent is the air which burn in the the cylinder. Also in this inlet and outlet valve is closed.

3. Power Stroke

In power stroke, The fuel and air is burnt because in the compression stroke piston compress the fuel  and air which burn the fuel and the air. Also in this inlet and outlet valve is closed.

4. Exhaust

In the exhaust valve, Inlet valve is closed and outlet valve is open and once again piston is go down and the mixture of air and fuel is go out through the exhaust valve.

Diesel Generator Set

The sub parts of engine which are connected inside the generator are: 

  1. Non Return Valve 
  2. Step Timing Control 
  3. Thermostat
  4. Fuel Shut Valve or FSO 
  5.  Motor 


Alternator is use to convert mechanical energy into electrical energy which is produced by the engine. Alternator works on the faraday’s law of electromagnetic induction that is when conductor cuts across magnetic field, E.M.F induce in it. Basically alternator is coupled with engine and load is connected at the alternator. Different parameters of the alternator is checked on the HMI like voltages, CT current, heating temperature, PMG etc.

There are two types of alternator one is with single bearing and other one is double bearing engine.

Single Bearing Engine

Single bearing alternator is also called AC generator. In these alternators, shaft is hold by single bearing at the non drive end. It is directly coupled with the engine. Single bearing alternator is easy to assemble as they require less maintenance  and cheap in cost as compared to the double bearing engine.

Double Bearing Engine

In double bearing engine, shaft is hold at the both end. Double bearing engine is very difficult to installed as compared to single bearing engine. The  alignment of  the shaft in these engine is very important because it has flexible coupling,  that’s why it consumes time. It require more maintenance as compared to the single bearing and cost is also high.

3. HMI

Human machine interface is use see the all parameter of the generator  which is connected with the generator. We can see parameters of engine, alternator and also radiator which comes on the HMI screen. Industries uses PCC2.1, PCC3.3 etc. In India mostly Cummins HMI are used.

Parameter Testing Report

During testing many factors are taking into the consideration like first they put 0% load on the generator and checked for 2 to 5 minute and then they put 25% then 50%, then 75% and then 100% and at last they put 125% and check all the parameter and write on the sheet. Mostly the generator was checked only for half an hour but if the owner of the generator is come then testing time is depend upon that person.


Filter is used in the generator to removed the unwanted particles which is not required in the generator. There are different type of filter which is used in the generator. The most common used filters are:

  • fuel filter
  • Coolant filter
  • Lubial filter
  • Fuel  water separator
  • Air filter
Fuel Water Separator

5. Turbo

In diesel generator ratio of air in the generator is 80% and the 20% is the diesel. For that fresh air turbo charge is used which take fresh air from the atmosphere which is very important. Vacuum indicator is used on the pipe of turbo charger which measures the pressure of the air but we have to checked the pressure manually. Air filter is used in the generator to remove the moisture content and unwanted content in the air. Then that air is passed through the compressor which compress the air. This compressed air is then goes in the piston cylinder with fuel and then it is burnt in that cylinder to create mechanical power.

6. Radiator 

Radiator is used to remove the heat in the diesel generator. Coolant and lubricant is used in the radiator to remove the heat. Lubricant is put around the piston and the coolant is first used to cool the lubricant and then that coolant is flow in the radiator. There are two types of radiator:

  1. Normal Radiator
  2. Plate Type Heat Exchanger or PHE Radiator   
Normal Radiator

Normal radiator basically has more size as compared to the PHE type radiator. PHE radiator is not normally used, it is used where the space is insufficient like in the basement or where the humidity is more, there this PHE radiator is used.

PHE Radiator


  1. In diesel generator as the name suggests diesel is used as fuel which is more efficient then petrol.
  2. Diesel is more reliable then petrol.
  3. Less pollution.
  4. In diesel generators with the help of canopy less noise produced.
  5. Less maintenance required.


  1. Initial cost is more.
  2. Diesel cost is increased with the sized of the generator.
  3. It is not easy to transport the generator from one placed to another.


  1. Diesel generator are used in the hospitals where continuous supply is required.
  2. Diesel generator are used for remote location where utility supply is not present or not continuous available.
  3. DG Set used in the shopping malls where continuous electrical supply is required.
  4. Diesel generator are used for military purposes.


Upinderdeep Singh is a 23 years old electrical engineer with strong passion. He lives in Jalandhar, Punjab. He did his bachelor from DAV Institute Of Engineering & Technology, Jalandhar.

Leave a Reply