Back Up Power Systems

CONTENTS

ACKNOWLEDGMENTS

PREFACE

LIST OF TABLES

LIST OF FIGURES

1 INTRODUCTION
1.1 Pretext
1.2 Methods of Generating Electricity
1.3 Common Power Problems

2 BACK UP POWER SYSTEMS IN INDIA
2.1 Indian Scenario
2.2 Back-Up Power Systems
2.3 Classification of Back-Up Power Systems
2.4 Common BPSs
2.4.1 Commercially Used BPS in India
2.5 Significance of BPSs
2.6 Advantages of Diesel Gensets over Other BPS
2.7 Performance Parameters of Diesel Gensets
2.7.1 Generator Factors
2.7.2 Alternator Factors
2.8 Need for Optimization
2.6 Motivation of Study

3 BACKUP POWER SYSTEMS: A REVIEW
3.1 Power Crisis
3.2 Origin & Evolution of BPS
3.3 Process Improvement of BPS
3.4 Six Sigma in BPS
3.4.1 Case Study I
3.4.2 Case Study II
3.4.3 Case Study III
3.4.4 Case Study IV
3.4.5 Some More Case Studies

4 BACKUP POWER SYSTEMS & SIX SIGMA
4.1 Research Gap
4.2 Problem Formulation
4.3 Methodology Proposed
4.3.1 Define Phase
4.3.2 Measure Phase
4.3.3 Analyse Phase
4.3.4 Improve Phase
4.3.5 Control Phase

5 A CASE STUDY OF DIESEL GENSET 101-149
5.1 Define Phase
5.2 Measure Phase
5.3 Analyse Phase
5.4 Improve Phase
5.5 Control Phase

6 CONCLUSIONS AND FUTURE SCOPE 150-155
6.1 Conclusions
6.2 Scope for Future

SOURCES

REFRENCES

FOR FUTURE READING

ANNEXURE-1

ANNEXURE-2

ANNEXURE-3

ANNEXURE-4

LIST OF TABLES

1.1 Sources of Electricity

1.2 Various Energy Resources

2.1 Performance Parameters

3.1 Applications of BPS and its Performance Improvements

3.2 Six Sigma-Some Definitions

4.1 Tools shortlisted for each phase of DMAIC methodology

4.2 Tools for Define phase

4.3 Tools for Measure Phase

4.4 Tools for Analyse Phase

4.5 Tools for Improve Phase

4.6 Tools for Control Phase

5.1 Load Distribution Chart

5.2 Diesel Expenses

5.3 Bias Checking

5.4 Seasonal Data of Mileage

5.5 Data for INNOVA Test on Cooling Temperature

5.6 Data for 2 Sample t-tests

5.7 Full Factorial Orthogonal Matrix

5.8 Designed Experiments

5.9 Plan for Control Phase

LIST OF FIGURES

1.1 Peak Demand

1.2 Classification of Power Generation

1.3 Cost of Production Per Unit

1.4 Book Plan

2.1 Commercial UPS

2.2 Genset Gas Turbine

2.3 Gas Genset

2.4 Diesel Genset

2.5 Diesel Genset Layout

3.1 Cummins Customer Satisfaction Strategy using Six Sigma

3.2 Process Output

4.1 High Power Generation Cost of various BPS

5.1 Genset

5.2 Running Time of Genset During 2010-2011

5.3 Monthly Diesel Oil Consumption

5.4 Process Mapping of Genset

5.5 Normality Test

5.6 Process Capability w.r.t. Mileage

5.7 Matrix Plot of Mileage vs. Oil Consumption

5.8 Bias Results

5.9 Fish Bone Diagram for Mileage

5.10 Multi Vary Analysis

5.11 Statistics of ANOVA

5.12 Graphical Representation of ANOVA results

5.13 Statistics of 2-t Test

5.14 Graphical Representation of 2-t Test

5.15 Main Effect Plot for Mileage vs Load

5.16 Pan for DoE

5.17 Normal Plot of Standardized Effect

5.18 Pareto Chart of Relative Impact

5.19 DoE Statistics

5.20 ANOVA on DoE Model

5.21 Main Effect Plots for Individual Factors

5.22 Two Way Interaction Plot

5.23 Three Way Interaction Plot

5.24 Mileage Vs AB Surface Plot

5.25 Contour Plot of Mileage Vs AB

5.26 Surface Plot of Mileage Vs AC

5.27 Contour Plot of Mileage Vs AC

5.28 Solution Given by Response Optimizer

5.29 Diagnostic Report

5.30 Process Spread after Improve Phase

5.31 Before/After Performance Comparison

5.32 Results Achieved in Actual

CHAPTER 1 INTRODUCTION

1.1 Pretext

Power has nowadays become a major commodity for everyone. From our homes to the small, big enterprises power is needed to run almost everything. No item or one can easily say that almost nothing runs without power. Hence in the past few years the demand of power has been increasing exponentially on a higher scale and in many areas world-wide. Because of its irregularity due to various economical and technical factors Backup Power Systems (BPSs) have come into spotlight.

The importance of electricity in our lives is known by everyone. All it requires is a power failure to remind us how much we are dependent on it. Imagining a life without electricity has become a nightmare i.e. no more instant light from flicking a switch, no more television, no more refrigerators, or stereos, or video games, or hundreds and thousands of other conveniences we take for granted. We are totally addicted to it, business relies on it and industry depends on it. Peak demand occurs when many people want electricity at the same time. Power companies need to be ready for such peak demands so that there is enough power for everyone. During the day’s peak i.e. between 12:00 noon and 6:00 p.m. supplementary generators must be used to meet this demand. These peak load generators run on natural gas, diesel, or hydropower and can be put into operation within minutes. The increase use of these generators results in the high generation of our utility bills. We can definitely help in keeping the costs down by properly managing the use of electricity during peak hours. This is illustrated in figure 1.1.

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Figure-1.1 Peak Demand (Source: The NEED Project 2011)

1.2 Methods of Generating Electricity

In order to transform various forms of energy into electrical energy directly there are seven significant methods:

- Static electricity, from the physical separation and transport of charge. (examples: tribo-electric effect and lightning)
- Electromagnetic induction, where an electrical generator, dynamo or alternator transforms kinetic energy (energy of motion) into electricity
- Electrochemistry, the direct transformation of chemical energy into electricity, as in a battery, fuel cell or nerve impulse.
- Photoelectric effect, the transformation of light into electrical energy, as in solar cells.
- Thermoelectric effect, direct conversion of temperature differences to electricity, as in thermocouples, thermopiles, and Thermionic converters.
- Piezoelectric effect, from the mechanical strain of electrically anisotropic molecules or crystals
- Nuclear transformation, the creation and acceleration of charged particles (examples: betavoltaics or alpha particle emission)

Turbines

Various fluids act as an intermediate energy carrier in all turbines. Most of the heat engines are turbines. Rest other types of turbines can be driven by wind or falling water.

Various Sources include:

Steam - Water is boiled by:

- Nuclear fission,
- The burning of fossil fuels (coal, natural gas, or petroleum). Gas turbines are directly driven by gases generated by the combustion of natural gas or oil. Combined cycle gas turbine plants are driven by both steam and natural gas. Power is generated by burning natural gas in a gas turbine and further use surplus heat to generate additional electricity from steam. The efficiencies of these plants are up to 60%.
- Renewable. The steam generated by:
- Biomass
- Solar thermal energy (the sun as the heat source): solar parabolic troughs and solar power towers collect sunlight to heat a heat transfer fluid, which is further used to produce steam.
- Geothermal power. Steam under pressure from the ground drives a turbine or at times hot water evaporates a low boiling liquid to create vapour in order to drive a turbine.
- Ocean thermal energy conversion (OTEC ): This technique uses the small difference between cooler, deep and warmer surface of ocean waters to run a turbine.

Other renewable sources

- Water (hydroelectric) - Blades in a turbine are acted upon by flowing water, produced by hydroelectric dams or tidal forces.
- Wind – Almost all wind turbines generate electricity from naturally flowing wind. An artificial wind is produced inside the chimney of a solar updraft towers by heating it with sunlight and hence it becomes a form of solar thermal energy.

Reciprocating Engines

Electricity generators are often powered by reciprocating engines through burning of diesel, biogas or natural gas. Usually at low voltages, diesel engines are used in often for backup power generation. Nevertheless most of the large power grids also use diesel generators, which are kept as an emergency back up for a specific facility such as a hospital, to feed power into the grid during uncertain circumstances. In a landfill or wastewater treatment plant, biogas is often produced by combustion with a reciprocating engine or a micro-turbine, which also is a small gas turbine.

Photovoltaic Panels

With various solar heat concentrators mentioned above, photovoltaic panels convert sunlight directly to electricity. Sunlight though being free and abundant, electricity generated from solar energy is still usually more expensive to produce than large-scale mechanically generated power due to the high cost of the panels. Silicon solar cells having low efficiency have been decreasing in cost and multi-junction cells with close to 30% conversion efficiency are now commercially available. Over 40% efficiency has been demonstrated in various experimental systems. Till date round the globe in various remote sites where there is no access to a commercial power grid or a supplemental electricity source, for individual homes or businesses photo-voltics are most commonly used. Recent advances in manufacturing efficiency and photovoltaic technology, combined with subsidies driven by environmental concerns, have impressively accelerated the deployment of solar panels. Germany, Japan, California and New Jersey are becoming the leaders in photo-voltics power generation and this has continuously grown by 40% every year.

Other Generation Methods

Various new technologies have been studied and developed for power generation. Solid-state generation (without moving parts) is of particular interest in portable applications. This area is largely dominated by thermoelectric (TE) devices, though thermionic (TI) and thermo photovoltaic (TPV) systems have been developed as well. TE devices are used specifically at lower temperatures than TI and TPV systems. Piezoelectric devices are used for power generation from mechanical strain, particularly in power harvesting. Beta-voltics, an another type of solid-state power generator produces electricity from radioactive decay. Fluid-based magneto-hydro-dynamic (MHD) power generation has also been studied as a method for extracting electrical power from nuclear reactors and also from more conventional fuel combustion systems. Areas where salt and sweet water merges (e.g. deltas), Osmotic power finally is another electricity generation possibility at such places.

For portable and mobile applications, electrochemical electricity generation has also come into limelight. Presently, most electrochemical power comes from closed electrochemical cells ("batteries"), which are utilized more as storage systems than generation systems. In the last few years open electrochemical systems, known as fuel cells, have been undergoing a great deal of research and development. Fuel cells can be used to extract power either from natural fuels or from synthesized fuels (mainly electrolytic hydrogen) and so can be viewed as either generation systems or storage systems depending on their use.

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Figure-1.2 Classification of Power Generation (Source: Wikipedia-2012)

The graph in figure 1.2 shows clearly the annual net generation of electricity in the world through various resources and we can determine clearly that fossil fuels are still amongst the major source of production of power. Similarly in the table1.1 we can clearly see the data collected in the year 2008 which depicts the power (electricity) production through various resources.

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Table-1.1 Sources of Electricity ( Source: IEA/OECD )

1.3 Common Power Problems

The primary role of any UPS (Uninterrupted Power Supply) is to provide short-term power when the input power source fails. However, most UPS units are also capable in providing solutions to varying degrees of common utility power problems like:

1. Power failure: defined as a total loss of input voltage.
2. Surge: defined as a momentary or sustained increase in the main voltage.
3. Sag: defined as a momentary or sustained reduction in input voltage.
4. Spikes: defined as a brief high voltage excursion.
5. Noise: defined as a high frequency transient or oscillation, usually injected into the line by nearby equipment.
6. Frequency instability: defined as temporary changes in the mains frequency.
7. Harmonic distortion: defined as a departure from the ideal sinusoidal waveform expected on the line.

In this book, the main attention is being given on the various aspects of energy conservation, power optimization, Six Sigma and its benefits in achieving the desired objective of enhancing mileage of diesel Gensets, wherever they are being used, be it in an organization, institution or industry. These back up power systems have created a revolution around us thus changing the way we look at the pace of growth of manufacturing or service sector. Hence keeping in mind the immense use of these BPSs many factors which enhance their overall performance/efficiency have been considered and well discussed in the various pages ahead thus providing the optimum solution for their better use.

Electricity Production Cost

The world wide data in the figure 1.3 (shown below) states that hydroelectric is the most cost effective form of power generation costing around $0.03 per kWh. Hydroelectric production is naturally limited by the number of feasible geographic locations and the huge environmental breach caused by the construction of a dam. Nuclear and coal are tied at $0.04 per kWh. This comes as a bit of a surprise because coal is typically regarded as the cheapest form of energy production. Another surprise is that wind power ($0.08 per kWh) came in slightly cheaper than natural gas ($0.10 per kWh).

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Figure-1.3 Cost of Production per Unit (Source: Nuclear Economy )

Solar power is by far the most expensive at $0.22 per kWh—and that only represents construction costs. Also, there is a higher degree of uncertainty in cost associated with wind and solar energy due to poor and varying data regarding the useful life of the facilities and their capacity factors.

Projected Costs of Generating Electricity nevertheless enables the identification of a number of tendencies that will shape the electricity generation sector in the years to come. The most important among them is the fact that where local conditions are favorable, nuclear, coal and gas are now fairly competitive generation technologies for base load power generation. Their precise cost competitiveness depends on the local characteristics of each particular market such as their associated cost of financing, amount of CO2 emissions and fossil fuel prices. As a matter of fact, the lower the cost of financing, the better will be the performance and competitiveness of capital-intensive, low-carbon technologies such as nuclear, wind and gas. There is no technology that has a clear overall advantage globally or even regionally. Each one of these technologies has potentially decisive strengths and weaknesses that are not always reflected in any research study.

Nuclear’s strength and its capability to deliver significant amounts of very low carbon base load electricity at costs has stablalized over time. However, it has yet to manage the high amounts of capital at risk and its long lead times for construction. Permanent disposal of radioactive waste, maintaining overall safety, and evolving questions concerning nuclear security and expansion remain issues that need to be solved for nuclear energy to become a global energy provider.

Coal on the other hand has its strength in its economic competitiveness in the absence of carbon pricing and neglecting other environmental costs. This applies in particular where coal is cheap and can be used for generating electricity close to the mines, such as in the western United States, Australia, South Africa, India and China. However, this advantage is considerably reduced where significant transport or transaction costs apply, or where carbon costs are included. The high probability of more generalized carbon pricing and more stringent local environmental norms thus drastically reduce its initial cost advantage.

Carbon capture [CC(S)] has not yet been able to demonstrate itself on a commercial scale for fossil-fuelled plant. In case of Carbon capture [CC(S)] power generating plants, an unproven rule of thumb says that transport and storage might add another USD 10 to 15 $ per MWh, thus making it quite expensive. Until a realistic number of demonstration plants have been operated for worthwhile time frames, total CC(S) costs will remain uncertain.

One of the great advantages of gas-fired power generation is its flexibility, its ability to maintain the right price in competitive electricity markets hedging financial risk for its operators and its lower CO2 profile. On the other hand, when used for base load power production it has comparatively high costs and is subjected to security of supply concerns in some regions. Progress in the extraction of lower-cost shale gas has eased the supply and demand balance and therefore improved the competitive outlook for natural gas in North America. Prices in this region are around half as compared to those based on oil-indexation in Continental Europe or the OECD Asia-Pacific region. For the very first time, onshore wind is included among the potentially competitive electricity generation. On the basis of the dynamics generated by strong government support, onshore wind is currently closing its still existing but diminishing competitiveness gap. Its only weakness is its variability and unpredictability, which can make system costs higher than plant costs. Although these can be addressed through geographic diversity and an appropriate mix with other technologies. According to the data available for this book, offshore wind is currently not competitive with conventional thermal or nuclear base load generation. Many renewable technologies, however, are immature, although their capital costs can be expected to decline over the next decade.

Once built renewable resources, like nuclear, also benefit from stable variable costs. If Projected Costs of Generating Electricity is an indication, the future is likely to see healthy competition between these different technologies, competition that will be decided according to national preferences and local comparative advantages. At the same time, the margins are so small that no country will be able to insulate its choices from the competitive pressures arising from alternative technology options. The choices available and the pressure on operators and technology providers to offer attractive solutions have never been greater. In the medium term, investing in power markets will be laden heavily with uncertainty.

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Table-1.2 Various Energy Resources (Source: 2008 US Electricity Generation)

Taking these results further the average energy cost per kWh around the globe is $0.059 as depicted in table 1.2. If we were to double the amount of nuclear energy by replacing existing coal capacity, the weighted average energy cost per kWh would be $0.058, a cost reduction of 1.7%. Tripling nuclear would yield $0.057, or a 3.5% overall cost reduction. This does not take into account the intangible costs we would save by reducing coal emissions by about 40% (80% if nuclear was tripled). There would also be 40% less coal required (80% if nuclear production was tripled), thereby reducing the impact of coal mining on the environment.

Nowadays it would be difficult, if not impossible, to imagine a world without electricity. Electric energy has wonderful properties for improving living conditions, for creating wealth and for providing widespread communication facilities. Electricity literally gives power to the people. That is why demand for electric energy will continue to increase. Producing the ever-increasing amounts of electricity needed in everyday life – from the most common domestic appliances to the vast demands of industry– is a challenge that needs to be met. Currently we are facing a future of ever-increasing demand for electricity and this demand must be fulfilled. Fortunately, at the moment we are equipped with more profound scientific knowledge and better technological capabilities than ever before. The research plan for the present work has been chalked in figure 1.4 below:

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Figure-1.4 Research Plan

A comprehensive literature survey has been done from various sources of media, print and electronic both have been very helpful in chalking out the base to carry out research on this subject. Research gap has been found through the intensive literature survey as most of the work on the Backup Power System (BPS) was being done qualitatively but there was no optimization suggested to solve the energy crisis through these BPSs which generates thousands of megawatts of electricity and this provides a major source of power to the domestic, industrial and agriculture sector. Henceforth problem formulation was been done highlighting the various problems, bottlenecks that come along the way both technically and economically Finally the methodology of Six Sigma implementation is been suggested which has a structured approach in optimizing these BPSs and validation of this methodology is done through an intensified case study of 320 KVA disel Genset over a large period of 12 months. After successful implementation of Six Sigma methodology groundbreaking results were achieved which resulted in approximately improvement of about 35% in nut shell. Main attention is being given to Six Sigma and its application to achieve desired objectives of enhancing mileage of diesel Gensets (as BPS). Diesel engine generator Set, or Genset as they are commonly called, are used primarily for emergency power generation or act as stand-by in case of power failure. Generators transform vitality from a mechanical kind to an electric sort, this strength then flows to an adjoining external circuit that conveys the ability towards the electrical appliances to run normally during power failures or cuts (Singh and Bakshi, 2014).

Things to Remember

- To imagine life electricity is next to impossible—no more instant light, no more television, or stereos, or video games no more refrigerators and hundreds of other conveniences we take for granted. People, business and industry depend upon it.
- Various sources of generating electricity are nuclear, thermal, hydro, coal, solar, petroleum, natural gas and various fossil fuels.
- The average energy cost per kWh around the globe is $0.059. The world wide data states that hydroelectric is the most cost effective at $0.03 per kWh and Nuclear and coal are tied at $0.04 per kWh.
- In 2008, India had approximately 177 gigawatts (GW) of installed electric capacity and generated 761 billion kilowatt hours. Conventional thermal sources produce more than 80 percent of India's electricity.

CHAPTER 2 BACKUP POWER SYSTEMS IN INDIA

2.1 Indian Scenario

India currently suffers from a major shortage of electricity generation capacity. In 2008, India had approximately 177 Giga watts (GW) of installed electric capacity and generated 761 billion kilowatt hours. More than 80 percent of India's electricity is produced by conventional thermal sources. Hydroelectricity, nuclear power and other renewable sources account for the remainder. India also imports marginal amounts of electricity from Bhutan and Nepal. India’s electricity generation capacity is very poor. According to the World Bank, roughly 40 percent of residences in India are without electricity. In addition, blackouts are a common occurrence throughout the country's main cities. India is a nation of more than a billion people. India's Bureau of Energy Efficiency (BEE) estimates that it will double or even triple over the next 20 years. As household appliances become the necessity of a happy middle class home, the burden on India's weak power grid will be breathtaking. Various power failure reasons are described in brief as follows:

Storms (wind, heat, lightning, thunderstorms, earthquakes, flood, and snow) are the most common cause of widespread power outages.

Trees can make contact with conductors during high winds, or limbs can fly into lines (especially palm fronds).

Vehicles often crash into utility poles. This can result in a service interruption. Earthquakes can cause damage to electrical facilities and equipment.

Animals (particularly birds and squirrels) can contact lines, causing service interruption.

Lightning can strike electrical equipment, including transmission towers, wires and power poles.

Excavation can damage underground cables.

Construction by outside contractors can cause damage to overhead lines and supports structures.

Equipment failure can cause outages.

High power demand can cause transformers to fail. Also electrical equipment can malfunction for a variety of reasons and under extreme conditions. A joint study by Manufacturers' Association for Information Technology (MAIT) and Emerson Network Power (India) said that India lost Rs 43,205 crore in financial year 2008-09 due to high occurrence of power outages, both scheduled and non-scheduled. It further said that the amount of such direct losses has more than doubled since 2003 when these amounted to Rs 22,000 crore.

2.2 Back-up Power Systems (BPS)

BPSs are a type of system, which may include lighting, generators, fuel cells and other apparatus, to provide backup power resources in a crisis or when regular systems fail. They find uses in a wide variety of settings from residential homes to hospitals, scientific laboratories, data centers, telecommunication equipment and modern naval ships. Emergency power systems can rely on generators, deep cycle batteries, flywheel energy storage or hydrogen fuel cells. Their diversified applications are listed below.

Applications

Operation in buildings: Power in main lines can be lost due to downed lines, malfunctions at a sub-station, severe weather, planned blackouts or in extreme cases a power grid failure. In modern buildings, most emergency power systems have been and are still based on generators. Usually, these generators are diesel engine driven, although smaller buildings may use a gasoline engine driven generator and larger ones a gas turbine. However, lately, more use is being made of deep cycle batteries and other technologies such as flywheel energy storage or fuel cells for power backup. The advantage of these latter systems is that they do not produce polluting gases, thereby allowing their placement to be done within the building. Also, as a second advantage, they do not require a separate shed to be built for fuel storage. With regular generators, an automatic transfer switch is used to connect emergency power. One side of the generator is connected to both the normal power feed and the emergency power feed; and the other side is connected to the load entitled as emergency. If no electricity comes in on the normal side, the transfer switch uses a solenoid to throw a triple pole, single throw switch. This switches the feed from normal to emergency power. The loss of normal power also triggers a battery operated starter system to start the generator, similar to using a car battery to start an engine. Once the transfer switch is switched and the generator starts, the building's emergency power comes back on (after going off when normal power was lost.)

Unlike, Emergency Lights emergency lighting is not a type of light fixture; it is a pattern of the building's normal lights that provides a path of lights to allow for safe exit, or lights up service areas such as mechanical rooms and electric rooms. Exit signs, Fire alarm systems and the electric motor pumps for the fire sprinklers are almost always on emergency power. Other equipment on emergency power may include smoke isolation dampers, smoke evacuation fans, elevators, handicap doors and outlets in service areas. Hospitals use emergency power outlets to power life support systems and monitoring equipment. Some buildings may even use emergency power as part of normal operations, such as a theater using it to power show equipment because the show must go on.

Critical Operations: At airports, Localizer, Glide slope and other instrument landing aids (such as microwave transmitters) are both high power consumers and mission-critical, and cannot be reliably operated from a battery supply, even for short periods. Hence, when absolute reliability is required (such as when operations are in force at the airport) it is usual to run the system from a diesel generator with automatic switchover to the mains supply in case the generator fails. This avoids any interruption to transmission while a generator is brought up to operating speed. This is a big advantage of emergency power systems, where the backup generators are seen as secondary to the mains electrical supply.

Electronic device protection: Computers, communication networks and other modern electronic devices need not only power, but also a steady flow of it to continue to operate. If the source voltage drops significantly or drops out completely these devices will fail, even if it is for a fraction of a second. Because of this, even a generator back-up does not provide protection because of the start-up time involved. To achieve this, extra equipment such as surge protectors, inverters, or a sometimes a complete uninterruptible power supply (UPS) is used. UPS systems can be installed locally or anywhere in the building premises.

A locally installed UPS is a small box that fits under a desk or a telecom rack and powers a small number of devices. On the other hand a UPS that is installed anywhere in the building premises can take on several different forms, depending on the application. It directly feeds a system of outlets designated as UPS feed and can power a large number of devices. Since telephone exchanges use DC (Direct Current), the building's battery room is generally wired directly to the consuming equipment and floats continuously on the output of the rectifiers that normally supply DC rectified from utility power. When utility power fails, the battery carries the load without needing to switch. With this simple though somewhat expensive system, some exchanges have never lost power for a moment since the 1920s.

2.3 Classifications of BPSs

A United States trade association known as NFPA (National Fire Protection Agency) defines various standards for the type of generator needed for your building and the delay time specifications for the actual system switch. According to NFPA regulations the generators are separated by it’s class, type, and level.

Classification According to the Coding System

Class: Class is determined by the amount of operation time a system can provide before it must be refilled with fuel. In most cases this distinction is represented by the word “Class” and a number. Fuel tank size and type determine the class of generator being used by your building.

Type: Type is defined by the length of time your building will experience actual power loss. A Type 60, for example, takes approximately sixty seconds to be in full operation. Those with a “U” supply uninterrupted power for items such as computers. Systems may also be manual, meaning an operator has to make a change for the generator to supply power.

Level: NFPA 110 levels apply to how the backup source will actually be used. A level one is necessary to ensure human safety while those designated as level two consist of all other building uses.

Classification According to the Space Availability

Portable generators : These are useful because they can be moved from location to location. They are most commonly used in residential applications and on construction sites where power is not available. The benefits of these Optional Standby portable generators can be very important though during a natural disaster. During the 2004 hurricanes in Florida, the use of generator engines was very common in residential neighborhoods as people awaited their power to be turned back on. To supply power to a refrigerator, coffee maker, television and a window air-conditioner a normal 5.5KW generator is sufficient.

Fixed-In-Place generators: These are commonly seen in commercial and industrial applications. They are becoming more popular in residential use but are not widely common. These types of generators can be very large which is why they are so common for large areas of assembly. The engine fuel that can be used is very diverse which is especially useful in various diversified projects.

Classification According to the Safety Requirements

Emergency (Life Safety): This classification of generators involves systems that supply loads that are essential to safety and life such as emergency lighting, exit signs, essential ventilation systems (especially in hospitals) and fire protection systems. Life Safety systems are installed in places of assembly such as high-rise buildings, schools, theaters, hotels, stadiums and any type of location where large groups of people gather. These systems are designed to provide illumination, during normal power outage, to ensure a safe means of exit. Life Safety systems also provide power for proper fire detection, continuous operation of fire pumps and fire alarm devices. As per global standards for these generators it is required to maintain enough fuel on-site to provide no less than 2 hours of operation and the system must turn on within 10 seconds of normal power shutting off.

Legally Required: This classification is very similar to Emergency systems with regard to where they are required. The main difference between the two is that legally required standby systems are intended to provide electric power to aid in firefighting, rescue operations, control of health, elevator usage, hazards and similar operations. The main focus of legally required systems is to "get people out of the building". During a power outage, a legally required Genset automatically (with 60 seconds) supplies power to selected loads that are not classified as emergency systems according to NFPA.

Optional Standby: Optional Standby Gensets are those that are not required by life safety, governmental agencies or the local enterprises. The requirements for these systems are dictated by the residential, commercial or industrial building owner(s), property managers and/or the businesses occupying them. Optional standby systems are intended to supply on-site power to selected loads either automatically or manually. The purpose for optional standby Gensets is to maintain power, during normal power outages, to either preserve inventory, prevent heat/humidity damage or to maintain normal working conditions following a natural disaster (hurricane, earthquake, etc). These Gensets can serve power to any system not classified as emergency or legally required such as power receptacles, domestic water booster pumps and water heaters, industrial machinery, freezers, refrigerators and/or UPS (uninterruptable power source) systems. Placement, installation, and maintenance are based on the set NFPA standards. A generator uses many components to actually send the needed current through electrical circuits.

2.4 Common BPSs

BPSs are type of systems, that includes lighting, generators, fuel cells and other apparatus to provide backup power resources in a time of crisis or when regular supply of electricity fails (Percebois, 2007). These systems find uses in a wide variety of settings from residential homes to hospitals, scientific laboratories, industries, data centers, telecommunication equipment and modern defense. Emergency power systems or BPS can rely on generators, deep cycle batteries, flywheel energy storage systems or hydrogen fuel cells. Irregularity of power supply in many areas worldwide and also due to diversify economical and technical factors, these BPS have come into limelight. BPS has created a revolution, changing the way of looking at growth of manufacturing or service sector (Smith, 2003). Hence keeping in mind the immense importance of these BPSs, many factors that enhance their overall efficiency have been well discussed in the pages ahead thus providing the optimum solution for their better use (Cobasys, 2012). Through present work, main attention is being given to Six Sigma and its application to achieve desired objectives of enhancing mileage of diesel Gensets (as BPS). Diesel engine generator set, or Genset as they are commonly called, are used primarily for emergency power generation or act as stand-by in case of power failure. Generators transform vitality from a mechanical kind to an electric sort, this strength then flows to an adjoining external circuit that conveys the ability towards the electrical appliances to run normally during power failures or cuts (Anna Bradd et al., 2008).

2.4.1 Commercially Used BPS in India

UPS (Uninterrupted Power Supply): An uninterruptible power supply, also known as uninterruptible power source, UPS or battery back-up, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A commonly used UPS is shown in figure 2.1.

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Figure-2.1 Commercial UPS (Source: UPS IEC-60230)

A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide instantaneous or near-instantaneous protection from input power interruptions by means of one or more attached batteries and associated electronic circuitry for low power users, and or by means of diesel generators and flywheels for high power users. The on-battery runtime of most uninterruptible power sources is relatively short 5–15 minutes being typical for smaller units—but sufficient to allow time to bring an auxiliary power source on line, or to properly shut down the protected equipment.

Gas Turbines: A gas turbine, also called a combustion turbine, is a type of internal combustion engine. As per the working of the turbine is concerned it has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbine's blades, thus spinning the turbine which powers the compressor and, for some turbines, drives their

mechanical output.

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Figure-2.2 Gas Turbine (Source: Thomas Sourmail -2009)

The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas. Energy can be extracted in the form of shaft power, compressed air or thrust or any combination of these and used to power aircraft, trains, ships, generators, or even tanks. A self explained gas turbine is shown in figure 2.2.

Gas Generator: A gas generator usually refers to a device, often similar to a solid rocket or a liquid rocket that burns to produce large volumes of relatively cool gas, instead of maximizing the temperature and specific impulse.

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Figure-2.3 Gas Genset (Source: China wholesale dealer)

The low temperature allows the gas to be put to use more easily in many applications, particularly to drive turbines. Gas generators are used to power turbo-pumps in rocket motors, to deploy airbags, and in other cases where large volumes of gas is needed, and storing it as a pressurized gas is undesirable or impractical. Figure 2.3 shows the setup of a gas generator.

Diesel Genset: A diesel generator is the combination of a diesel engine with an electrical generator (often called an alternator) to generate electrical energy. Diesel generating sets are used as emergency power-supply unit in places without connection to the power grid, in case the grid fails. Also these are used well for more complex applications such as peak-lopping, grid support and export of electricity to the power grid. Sizing of these diesel generators is critical to avoid low-load or a shortage of power and is complicated by modern electronics, specifically non-linear loads. Figure 2.4 shows the complete diesel generator set or Genset as its called.

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Figure-2.4 Diesel Genset (Source: Cummins)

The packaged combination of a diesel engine, a generator and various ancillary devices (such as base, canopy, sound attenuation, control systems, circuit breakers, jacket water heaters and starting system) is referred to as a "generating set" or a "Genset" for short.

2.5 Significance of BPSs

BPSs like Gensets are commonly used primarily in emergency power generation or stand-by power in case of power failure. In the case of emergency power the Gensets are extremely important piece of equipment for hospitals, utilities, and government buildings. Stand-by Gensets provide back-up power for many financial and data companies that rely on power to facilitate their day to day operations. As noticed, many of these facilities are familiar and located in our neighborhood or near noise sensitive areas. Here lies the importance of Genset noise control and acoustical enclosures. The diesel power generators provide insurance and piece-of-mind in an emergency. Gensets typically need to be tested on a regular schedule to insure operation in case of an emergency.

One of the most significant inventions that could also be termed as most helpful is that of generators, capable of delivering strength to all the fundamental utilities needed for an individual's use that require the use of electrical energy. Most appliances utilized in homes and even nearly in the industries call for electrical energy in order to function. This need of continues electric energy is efficiently covered through the commendable invention of generators, which has become a clear boost for industrialization and other upcoming inventions. Hospitals, substantial industries and other major enterprises of production require the simple know-how related to generators so as to function within a stable and productive way. Industries, hospitals as well as other platforms cannot incur severe losses, harm to components or even fatalities every time there is certainly energy disruptions. Hospitals specifically run daily life supporting and preserving equipments which demand regular offer of electrical energy otherwise there can be drastic loss of lives. Generators perform purely by transforming of vitality from a mechanical kind to an electric sort, this strength then flows to an adjoining external circuit which conveys the ability towards the required electrical appliances. Magnets and copper coils are the basic parts in the motors that convert the power rather than creating it. Some with the elementary gear accustomed to supply the mechanical power consist of turbine steam engines, steam engines and internal combustion engines, reciprocating steam engines, wind turbines and mineral water wheels amongst others.

2.6 Advantages of Diesel Gensets over Other BPSs

There are various advantages of diesel powered Gensets over other BPSs. The diesel engine is much more efficient and preferable as compared with gasoline engine due to the following reasons:

- Modern diesel engines have overcome disadvantages of earlier models of higher noise and maintenance costs. They are now quiet and require less maintenance as compared with gas engines of similar size.
- They are more rugged and reliable.
- There is no sparking as the fuel auto-ignites. The absence of spark plugs or spark wires lowers maintenance costs.
- Fuel cost per KiloWatt produced is thirty to fifty percent lower than that of gas engines.
- Gas units burn hotter than diesel units, and hence they have a significantly shorter life compared with diesel units

2.7 Performance Parameters of Diesel Gensets

Performance metrics refers to the various factors or parameters which affect the overall performance of the process or the product. Hence it’s become very vital to calculate and find out various such parameters which are affecting the process as a whole or the production throughout. Hence for BPSs also there are various such performance metrics which are discussed in detail and are enlisted below. Various parameters which affect the performance of the Diesel Genset are enlisted in the table 2.1 below:

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Table-2.1 Performance Parameters

(Source: Product Specification Template-3c)

Energy characteristics:

There are a number of important factors to consider when examining the abilities of power generation equipment.

Energy return on investment: Energy return on energy invested (EROEI) is the ratio of the amount of electricity produced by a piece of equipment over the amount of energy required to create that piece of equipment. For example, if during its entire lifetime a hydroelectric turbine created 100 MWh of energy and it took 2 MWh to build the turbine, then the EROEI of this turbine would be 50. EROEI is important because it puts some fundamental limits on how quickly we can add power generation to our grid. For example, in the above example of the hydro turbine should be able to, during its lifetime, pay back the energy debt for its own construction and then a surplus of 98MWh. This could in theory provide enough energy for the creation of 49 more turbines like it. This number is rather high. Most fossil fuel and nuclear power systems that are used globally have smaller EROEIs in the range of 4 to 20.

Energy payback time: Energy payback time is closely related to the EROEIs which were just looked before. Energy payback time refers to how long a piece of power generation equipment needs to be in operation before it creates the same amount of usable electricity as the amount of energy that went into constructing it. Energy payback time can be calculated from the EROEI if the average lifetime of the power plants used to create the EROEI estimate is known. Henceforth just take the lifetime and divide it by the EROEI to get an estimate of the energy payback time. For example, an article estimates the energy payback time of concentrated solar thermal power around 8 months, which is a very impressive number. Energy pay back times for photovoltaic’s are estimated by the National Renewable Energy Laboratory in the United States to be between 1 and 3.8 years, depending on the technology and implementation. Again, these are very impressive numbers. An earlier citation fromReal Energy gives some useful numbers for the calculation of energy payback times from EROEIs. It is clear that most of the conventional fossil fuel sources have relatively high energy payback times while the currently developing renewable sources are quite impressive.

Lifetime: The lifetime of a proposed power plant is important for a number of reasons. Long-term planning by power authorities will examine the entire lifecycle of the power resource. The lifetime of a power system will also affect planning by local communities and investors.

Dispatchability: Essentially if a power system is ‘dispatchable’, it means that it can be turned on and off within seconds, minutes, or hours. If a power system takes most of a day to turn on, it is likely to be considered a base load source rather than a dispatchable one.

Intermittency: Power sources that are intermittent i.e. occasional are power sources that are not base load or dispatchable. These are sources such as wind power and solar photovoltaics that only produce power when there is wind or sunshine respectively. In the case of wind power, it is worth mentioning another facet of its limitations. Some areas of the world experience temperatures below -20ºC. In these places, wind turbines often have an automatic shutdown temperature at around -30ºC. This is not always the case however, since there are functioning wind turbines on Antarctica where it gets much colder. However, the fact remains that many wind power installations do not produce power when it is extremely cold.

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