eChapters

6.0 General

No lessons can be drawn without the experiences of the past. In fact, much of engineering, rather all sciences have developed in bits and pieces from the experiences of the past. The engineers by and large have never become wiser in one day. They have become wiser slowly and slowly with their own experiences and from the experiences of past engineering works. Wisdom lies to gain wisdom from experiences/draw lessons from the marvellous engineering works constructed so far. It helps us in a direction for further development of technological skills.

Here an effort is made to draw lessons from experiences of the canals constructed in the past.

 There are several aspects of such experiences. A few important aspects of studies are:

 (i) Internal hydraulic sections of the canal with respect to discharge, topography, stability of side slopes, type of lining, operation and maintenance problems and their solutions etc.

 (ii) Design of canals banks (embankment) with respect to discharge, depth of flow, depth of cutting /filling, below/above natural ground level, type of soil, topography, operation and maintenance, drainage of banks etc.

 (iii) Canals aesthetics and arboriculture

 (iv) Other utility/service of canal such as multi-objectives of hydropower, irrigation, drinking/industrial water supply, social needs of recreation, forests etc.

A. Rectangular Canals

5.1 Design of Best Rectangular Canals

After the Mehboob and Trapezoidal canals, next best section is rectangle. This section is also generally adopted for small discharges say upto 10 cumecs (350 cusecs). This section ranks at No. 4. Yet, this is the only section most commonly adopted for flumes of discharges upto140 cumecs (5000 cusecs). Typical example is Orsang acqueduct, 1 km. long for 1140 cumecs (40000 cusecs) in ractangular sections on Narmada Canal Project, Gujrat, India, built in the years from 1990 – 2000. Such sections are common in power house canals due to limitation of space and very sharp curves. It is free from the effect of change of side slopes as in the trapezoidal canals (see para 3.3) Still some small side slope (batter) is adopted in thick masonry / concrete lining. It adds to structural stability with economy in thickness of wall and as well as hydraulic efficiency. It may still be called as rectangular section.

Details of its hydraulic efficiency in comparison to semi circle, Mehboob and trapeziodal sections are discussed in chapter 1, para 1.8

A canal of more than 80 cumecs (3000 cusecs) approximetly may be called as a high capacity canal.

It has already been pointed out in chapter 1, that for the best section of any shape, R is always equal to d/2 only, and such depth is the most optimum depth. But such channels are not always practical or most economical due to many other practical reasons, (see para 4.1 and 6.3) and many times shallower depth then this depth is adopted. Typical examples are lining of existing earthen channels, given in para 6.3.

All the best sections have fixed ratio of dimensions very near to the semi circle. For large discharges, radius of semi circle increases that, means depth of canal as well as velocity increases. But higher velocity is not permissible with every type of lining (see table 2.1 and para 2.3). Similarly depth also has limitation of construction, maintenance, stability of slopes, etc. see example–4.2.

Because of limiting velocities and depth, deeper canal section are not practically feasible/possible. Therefore for large discharges, say more than 100 cumecs, Mehboob or best trapizodal sections are just not possible/practical, and recourse has to be taken to trapezoidal section with increased bed width then depth. This section is hydraulically inefficient or uneconomical. Larger the B/D ratio, larger is the inefficiency and section is more costly. (For Mehboob Section, B:D ratio is zero and for best trapizodal section it is much less than 1, see para 3.1, table 3.1 para 3.5 and table 3.4).

A canal of approximate discharge of less than 80 cumecs (3000 cusecs) discharge may be called a medium or low capacity canal).

3.1 Mehboob Section

A Mehboob Section is only a modification of best trapezoidal section by making its complete bottom circular as shown in figure 3.1. Also see figure 1.6 and para 1.7. That is why these canals are also known as canals of zero bed width, or trapezoidal canals with curved bottom, or cup shaped canals.

But these cannot be called as triangular canals with curves, as often spoken. In fact it is a truncated triangle circumscribing the semi circle. Trapezium is also a truncated triangle circum scribing a circle.

More accurately it can be said as a combination of semi circular and best trapezoidal section so as to take full advantage of their hydraulic efficiency and practicability.

This is such a beautiful section that the designer can never commit a mistake, even if he wants to commit a mistake. The dimensions are so geometrically fixed that no one can play with any dimension.

The value of this section was realised for the first time by Er S I Mehboob (1943) in his Punjab Irrigation Branch Paper No.260" Lining of Canals". There after this canal section became well known as Mehboob Section after his name. He also stated that the most economical section i.e. the maximum area for the minimum perimeter is when the centre of the arc is at the full supply line of the section. This is also evident in figure 1.6. This is also the condition for all best hydraulic sections. This section is also useful to a higher silt carrying capacity than a wide shallow one..

 

 

Theoritical aspects of design has been discussed in chapter 1. Discharging capacity of canal is

 computed by Manning Equation (1)and continuity Equation (2) (Para 1.4).

 In the Manning's equation  V  =   R2/3  S1/2 / N (Eq. 1, Para 1.4);  N and R play most important role.

 The effect of  R has been discussed in para 1.4.1, Chapter 1. In this chapter the complexities of Manning's n (or N, also known as Manning's rougosity coefficient

 or simply rougosity coefficient) and some practical aspects of composite sections and velocity in best

 Mehboob, trapezoidal or rectangular sectioned channels are discussed.

2.0 Manning's Rugosity Coefficient (n)

Value of N depends upon a number of factors such as , surface roughness, vegetation, obstructions, type of lining, age of lining, erosion and damages in lining, curves, discharging capacity , perimeters, depth of flow, velocity etc. These are discussed below and commonly adopted values of n are given in tables 2.1 to 2.3.

 

1.0 General

 The design of canal involves following three major aspects:

 A Irrigation and drainage canal network planning.

 B Determination of discharge / capacities of  canals and drainages.

 C Determination of shape and size i.e. geometrical dimensions of the proposed canal section, generally

 known as design of canal section. More appropriately it can be called as design of internal section

 of canal. It can be further divided in three following parts viz.

 i. Design of unlined canals:

 ii. Design of lined canals: or a canal may be partly lined and partly unlined.

 iii. Choice between the unlined and lined canals. This aspect should be distinguished from the selection of type of lining. However, the scope of choice of lining may include both the aspects.

 The design of canal section remains incomplete without the design of its embankments, either in lined or unlined canal, so the next aspect is

 iv. Design of canal embankments. Still to complete the design of a canal one more aspect is required i.e.

 v. Canal aesthetics and canal arboriculture.

1. The first scientific account of the lac insect was given by …. . . .

 a) J. Kerr (1782) b) W.Kritz (1882)   

 c) Pamella Britz (1888) d) None of these

 2. The scientific name of lac insect is …. . . .

 a) Tachardia lacca b) Tachardia indica   

 c) Tachardia suzi d) Tachardia essart

 3. Lac is secreted by insects for …. . . .

 a) Feeding b) Reproduction  

 c) Protection from predators d) Both a & b

 4. The life cycle of lac insect takes about …. . . months.

 a) Two months b) Six months   

 c) Ten months d) Twelve months

 5. The life cycle of lac insect consists of …. . . .

 a) Nymph instar b) Pupa   

 c) Adult  d) All of these

1. The rearing of earthworms for composting wastes into valuable nutrients

is known as …. . .

 a) Organic farming b) Organic manuring

 c) Vermitechnology d) Sustainable technology

 2. Vermitechnology provide …. . .

 a) Vermiwash b) Vermicompost

 c) Organic fertilizer d) All of these

 3. Vermicompost improves …. . . property of soil.

 a) Physical b) Chemical

 c) Biological d) All of these

 4. In class oligochaeta …. . .

 a) Parapodia  absent b) Clitellum present

 c) Pharynx without jaws d) All of these

 5. In which order earthworm is placed?

 a) Oilgochaeta b) Frrantia

 c) Neooligochaeta d) Sedentaria

1. …. . involves rearing of silkworms.

 a) Lac culture b) Sericulture  

 c) Apiculture d) Pisciculture

 2. ‘Silk Samagra’ scheme was launched by …. . .

 a) Government of Karnataka b) Government of Tamil Nadu  

 c) Government of Punjab  d) Government of India

 3. Match the pairs

 a) Mulberry silkworm          1. Antheraea paphia

 b) Tasar silkworm                  2.  Attacus ricinii

 c) Muga silkworm                 3.  Antheraea pernyi

 d) Eri silkworm                        4.  Attacus altas

 e) Oak silkworm                     5.  Bombyx mori

 f) Giant silkworm                  6.  Antheraea assama

 a) a=5, b=2,c=3,d=4,e=1, f=6 b) a=5, b=1, c=6, d=2, e=3, f=4

 c) a=2, b=4, c=3, d=1, e=6, f=5 d) a=2, b=3, c=2, d=1, e=4, f=6

 4. ‘Silk Samagra’ scheme was launched for period of …. . .

 a) 2017-2020 b) 2016-2019 

 c) 2014-2017 d) 2021-2024

1. ‘Apis’ means …. . .

 a) Waxf b)   Bee      

 c)  Honey d) All of these

 2. Apiculture is also known as …. . .

 a) Bee-keeping b) Wax preparation                

 c) Both a & b d) None of these

 3. Importance of bee-keeping …. . .

 a) It provides honey      

 b) It provides bee wax             

 c) Honey bees are excellent pollinating agents, thus increasing agricultural

 d) All of these

 4. Species of honey bee is …. . .

 a) Apis dorsata b) Apis indica             

 c) Apis florae d) All of these

1. Rearing of fowls for eggs and flesh is known as  ….

 a) Poultry keeping b) Husbandry   

 c) Sericulture d) Apiculture

 2. The types of poultry birds are  ….

 a) Broilers b) Layers  

 c) General purpose birds d)  All of these

 3. The layers are reared mainly for  ….

 a) Flesh b) Eggs  

 c) For both d) None of these

 4. Which of the following are layers?

 a) Anconas  b) Australorp   

 c) White leghorn d) All of these

 5. Broilers are reared for  ….

 a) Flesh b) Fish  

 c) Ornamental purpose d) All of these

1. Which period is known as the ‘operation flood era’?

  a) 1971 and 1996     b) 1978 and 1999

  c) 1969 and 1974    d) 1974 and 1978

 2. In which year Indian government launched ‘operation flood program’?

   a) 1970     b) 1950

 c) 1960   d) 1972

 3. Which is the largest milk producer in the world?

   a) China   b) Germany

 c) Russia   d) India

 4.  ‘White Revolution’ in concerned with .........

   a) Egg production   b) Meat production

 c) Grain production  d) Milk production

1. Corals are .........

 a) Animals b) Plants

 c) Diatoms d) Plankton

 2. Corals belongs to which phylum?

 a) Protozoa b) Echinodermata

 c) Cnidaria

 3. The corals consists of a sac-like structure called .........

 a) Septa b) Polyp

 c) Haloclone d) Nephris

 4. ......... build reefs found in shallow tropical seas.

 a) Hermatypic corals b) Ahermatypes corals

 c) Both a & b d) None of these

 5. ......... per cent of the corals are located in the Indian ocean,Red sea and Persian Gulf.

 a) 30% b) 5%

 c) 10% d) 70%

1. Which of the following is an example of freshwater mussel?

 a) Lamellidens marginalis b) Lamellidens corrianus

 c) Pictada fucata d) Both a & b

 2. ......... is secreted by the mantle of the pearl oyster as a protection against foreign objects.

 a) Pearl b) Swarm

 c) Prismatic layer d) Nacreous layer

 3. Shell of pearl oyster is composed of ......... layers.

 a) Two b) Three

 c) Four d) Five

 4. Which is the outermost layer of shell?

 a) Prismatic layer b) Nacreous layer

 c) Periostracum layer d) None of these

 5. ......... is the outermost, greenish-brown, thin, translucent layer made up of conchiolin.

 a) Nacreous layer  b) Mantle

 c) Periostracum d) Perismatic layer

1. Live feed is also known as .........

 a) Natural food b) Fish food organisms

 c) Both a & b d) Algae

 2. Live feed are organisms used as food by .........

 a) Prawns b) Carps

 c) Oysters d) All of these

 3. The common phytoplankton used as live feed are…………

 a) Eudorina b) Volvox

 c) Pediastrum d) All of these

 4. The common  zooplankton used as live feed are .........

 a) Vorticella b) Artemia

 c) Cyclops d) All of these

1. The word aquarium for the first time was used by ..........

 a) Philip Henry Gosse   b) Anne Thynne

 c) Philip Rottz   d) Britz Carles

 2. Who built the first stable marine aquarium in 1846?

 a) P.H.Gosse       b) Philip Rottz

  c) Britz Carles      d) Anne Thynne

 3. In 1853,the first large public aquarium was opened in .........

  a) Roman empire         b) London zoo

    c) Victoria era       d) None of these

4. Taraporewala aquarium came into existence in .........

 a) Year 1951       b) Year1945

   c) Year 1974        d) Year 1981

1. To which family freshwater prawn belong?

 a) Arthropoda b) Crustacea

 c) Palaemonidae d) Malacostraca

 2. Scientifc name of freshwater prawn is .........

 a) Penaeus monodon b) Scylla serrata

 c) Macrobrachium rosenbergii d) Metapenaeus monoceros

 3. Freshwater prawn is also known as .........

 a) Giant river prawn b) Scampi

 c) Banana prawn d) Both a & b

 4. Identification features of freshwater prawn are .........

 a) Presence of grey and longitudinal streaks of light and dark colour

 b) The largest pereiopod of adult male is dark blue.

 c) The eggs of berried female are yellow in colour

 d) All of these

1. Indian Major carps belongs to which family?

 a) Cobitidae

c) Ariidae

b) Cyprinidae

 d) Clupeidae

2. Body of carps is covered by which scales?

 a) Placoid

b) Ganoid

 c) Cycloid

3. Family cyprinidae includes......

 a) Catla catla

c) Cirrhina mrigala

d) Ctenoid

 b) Labeo rohita

 d) All of these

4. Selection criteria for cultivable fish includes .........

 a) It should have a fast growth rate

 b) It should be a hardy and resistant to disease

 c) Its flesh should be tasteful and with high nutritive value

 d) All of these

5. Why carps are suitable for culture?

 a) They can tolerate low oxygen content

 b) They have fast growth rate

 c) They feed on plankton,decaying weeds and debris

 d) All of these

Introduction to strategy implementation involves translating strategic plans into actions and achieving desired outcomes. While many organizations focus on the technical aspects of implementation, it is crucial to consider the behavioral dimensions as well. Behavioral dimensions encompass the attitudes, behaviors, and actions of individuals within an organization that impact the success of strategy implementation. Here are some key points to consider regarding the behavioral dimensions of strategy implementation:

Organizational culture: The culture of an organization plays a significant role in strategy implementation. It comprises shared values, norms, beliefs, and practices that influence employee behavior. An accommodating and flexible culture fosters employee engagement, commitment, and alignment with strategic goals.

Leadership and Communication: Effective leadership is essential for successful strategy implementation. Leaders must articulate the strategy clearly, provide guidance, and motivate employees towards the desired outcomes. Communication channels ought to be open, transparent, and promote a culture of collaboration and feedback.

Employee Involvement and Empowerment: Involving employees in the strategy implementation process increases their commitment and ownership. Empowering employees through delegation of authority and decision-making cultivates a sense of responsibility and accountability, leading to enhanced performance and innovation.

Introduction

It refers to action which are taken with an aim to provide value to customers developing a competitive advantage by encashing upon the strength areas. In case of business Organisation with multiple business, where each business is considered as Strategic Business Unit (SBU).

• It address the following issues

 • Satisfying the Customer needs

 • Achieving an edge over its competitors

 • Avoidance of competitive disadvantage

Michal Porter Generic Competitive Strategy aim to develop position in long run to outperform the competitors. The three strategies includes:

• Cost Leadership: Providing quality product at low cost

• Differentiation: Providing unique goods and services

• Focus: Cost and differentiation focus

Introduction to Evaluation in Strategic Management Process

Strategic management is the process of formulating and implementing strategies to achieve an organization's goals and objectives. It entails making decisions and taking actions that align the organization with both its external environment and internal capabilities. Evaluation is a crucial component of the strategic management process as it helps assess the effectiveness and efficiency of the strategies implemented. It involves the systematic and objective assessment of various aspects of the organization's performance, including its strategy, resources, operations, and outcomes. The primary purpose of evaluation in strategic management is to determine whether the strategies are yielding the desired results and to identify areas for improvement. It offers valuable insights into the organization's strengths, weaknesses, opportunities, and threats, enabling informed decision-making and adjustments to strategies as necessary.

Introduction

The strategic control process is an essential component of strategic management that helps organizations monitor and evaluate their strategic plans and initiatives. It involves a systematic approach to assess the progress performance, and effectiveness of strategic objectives and make necessary adjustments to ensure alignment with organizational goals. Here are some key points on the introduction to the strategic control process. Strategic control refers to the ongoing monitoring, evaluation, and adjustment of an organization's strategic activities to ensure they are in line with the desired outcomes and objectives. It The significance of strategic control lies in several key reasons. helps organizations track their progress, identify deviations from the intended course, and take corrective actions. It also enables managers to assess the effectiveness of strategies, make informed decisions, and enhance organizational performance.

Introduction to Corporate Governance

Corporate governance encompasses the framework of rules, practices, and processes that guide the direction, control, and management of a company. It involves the interactions among various stakeholders, including shareholders, management, the board of directors, employees, customers, suppliers, and the community. Successful corporate governance is vital for a company's long term success and sustainability. It helps establish a framework for responsible decision-making, accountability, and transparency, which enhances investor confidence and protects the interests of stakeholders.

 

Introduction to Corporate Level Strategy

Corporate level strategy pertains to the choices and initiatives undertaken by a company's senior management to define the overarching direction and breadth of the organization. It entails making decisions regarding which industries or markets to engage in and how to distribute resources among various business units.

Scope of Decision-Making: Corporate level strategy concentrates on the entirety of the organization rather than individual business units or functional areas. It involves strategic decisions related to diversification, vertical integration, mergers and acquisitions, strategic alliances & resource allocation.

Purpose: The primary goal of corporate level strategy is to create value for shareholders by achieving a sustainable competitive advantage and maximizing the overall performance and profitability of the organization. It involves assessing the external business environment, identifying opportunities and threats, and leveraging internal capabilities to gain a competitive edge.

Diversification: One key aspect of corporate level strategy is deciding whether to pursue a strategy of diversification. Diversification can be either related (expanding into industries or markets related to the company's current business) or unrelated (entering completely new industries). The decision to diversify involves assessing the potential benefits, risks, and synergies associated with entering new markets.

Introduction

It includes different levels of competitive strategy and how generic competitive strategies can be formulated. The organisation need to understand how to tackle the competitors and what specific decisions to be taken while formulating a competitive strategy. Each type of industry has to plan its own competitive strategy either to grow or to come out in bad situation. Michal Porter described generic competitive strategies to cope with five competitive forces. These strategies help organisation in different situation to develop appropriate competitive strategy that can be implemented effectively.

Competitive strategies are the methods and approaches used by companies to gain a competitive edge in the market and surpass their rivals. These strategies involve making deliberate choices about how to position the company, allocate resources, and respond to market conditions. Here are some key points to consider when introducing competitive strategies.

Introduction to Internal Environment Analysis

Internal environment analysis is a critical component of strategic management that focuses on evaluating an organization's internal factors and resources. It involves assessing the internal strengths and weaknesses to gain insights into the organization's capabilities and competitive advantage. Here are some key points to highlight when discussing the introduction to internal environment analysis:

Internal environment analysis refers to the process of examining and evaluating an organization's internal factors, including its resources, capabilities, and core competencies. It helps identify strengths and weaknesses that can influence the organization's performance and competitiveness.

Purpose: The primary purpose of internal environment analysis is to understand the organization's internal dynamics and uncover key areas where it has a competitive advantage or faces challenges. It enables organizations to identify their core competencies and allocate resources effectively to achieve strategic goals.

Introduction to Competitive Analysis

Competitive analysis is a crucial component of strategic planning and business decision-making. It involves assessing and understanding the competitive landscape in which a company operates. Here are some key points to consider when introducing competitive analysis:

Competitive analysis is the process of evaluating and analyzing the strengths and weaknesses of current and potential competitors in a specific market or industry.

Purpose: The primary purpose of competitive analysis is to gain insights into competitors' strategies, capabilities, and market positioning. It assists businesses in pinpointing opportunities, mitigating risks, and formulating effective strategies to surpass their competitors.

Information sources: Competitive analysis relies on gathering information from various sources. These include publicly available data, industry reports, competitor websites, customer reviews, social media, and market research.

Introduction

External environmental analysis is a critical process that organizations undertake to assess and understand the various factors and forces that exist outside their immediate operational boundaries.

It involves examining the external environment in which a business operates to identify opportunities, threats, and potential influences that may impact its performance and strategic decisions.

External environmental analysis is the systematic evaluation of factors outside an organization's control that can significantly impact its operations, strategies, and overall success.

Purpose The aim of conducting an external environmental analysis is to acquire a deeper understanding of the opportunities and threats that exist within the external environment. By comprehending these elements, organizations can make informed choices and craft efficacious strategies to adjust and prosper in an ever-evolving business environment.

Factors to Analyze: Highlight the main factors that organizations typically analyze during external environmental analysis. These encompass the Political, Economic, Social, Technological, Environmental, and Legal (PESTEL) factors.. Additionally, industry-specific factors such as competition, customer behavior, and market trends should also be considered.

Tools and Techniques: Briefly mention some common tools and techniques used in external environmental analysis. These methodologies may involve SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis, the application of Porter's Five Forces framework, scenario planning, trend analysis, and market research.

Introduction

Strategy in the global context requires a thorough understanding of the external environment, including economic, political, cultural, and technological factors that could impact an organization's operations. Organizations must also understand their internal strengths, weaknesses, opportunities, and threats to develop effective strategies that align with their goals. A global strategy involves developing a standardized approach to business activities that can be applied across different countries and cultures, while also adapting to local Market Conditions. Companies that operate globally must consider the differences in legal and regulatory environments, cultural norms, and consumer preferences when developing their strategies. Global strategy requires collaboration across different regions and functions within an organization to achieve a shared vision and common goals. The use of technology and data analytics is crucial in developing and executing global strategies, as it can help organizations identify new market opportunities, monitor changes in the external environment, and make informed decisions. Companies achieving success in formulating and executing global strategies must demonstrate agility and rapid adaptability to external environmental shifts. Additionally, they should maintain a steadfast commitment to continuous improvement and innovation to maintain a competitive edge.

Introduction

Strategy is a critical aspect of any organization, as it helps to align resources, capabilities, and competencies to achieve the goals and objectives of the organization.

Strategic Management Process: The strategic management process com prises four essential stages: analysis, formulation, implementation, and evaluation. Each stage plays a crucial role in attaining desired outcomes and maintaining the organization's competitiveness.

Analysis Stage: During the analysis stage, the organization thoroughly examines its internal and external environments. The internal analysis assesses the organization's strengths and weaknesses, while the external analysis explores the opportunities and threats present in the market.

Formulation Stage: The formulation stage involves developing strategies to achieve the goals and objectives of the organization. This stage involves selecting the most appropriate strategy based on the results of the analysis.

Introduction

Strategy is to achieve a particular goal or set of goals through plan of action. Importance of strategy: Strategy helps organizations to focus on their longterm goals and objectives, and to allocate their resources in the most effectiveway to achieve those goals.

 Types of strategy: There are several types of strategies, including corporatestrategy, business-level strategy, functional-level strategy, and operationalstrategy.

 The strategy development process: The strategy development processtypically involves several steps, including analyzing the external and internalenvironment, setting objectives, formulating a strategy, implementing thestrategy, and evaluating the results.

 Organizational strategy tools and techniques: Numerous tools andtechniques exist for organizations to foster and execute their strategies. These encompass SWOT analysis, PESTLE analysis, Porter's Five Forces analysis, and the Balanced Scorecard.

 

Solar Photovoltaic

A single solar cell cannot provide required useful output. Therefore, to increase output power level of a PV system, it is required to connect number of such PV solar cells. A solar module is normally series connected sufficient number of solar cells to provide required standard output voltage and power. One solar module can be rated from 3 watts to 300 watts. The solar modules or PV modules are commercially available basic building block of a solar electric power generation system.

Actually, a single solar PV cell generates very tiny amount that is around 0.1 watt to 2 watts. But it is not practical to use such low power unit as building block of a system. So required number of such cells are combined together to form a practical commercially available solar unit which is known as solar module or PV module.

Inroduction

The process of connecting neutral point of 3-phase system to earth (i.e. soil) either directly or through some circuit element is called neutral grounding. Neutral grounding provides protection to personal and equipment. It is because during earth fault, the current path is completed through the earthed neutral and the protective devices (e.g. a fuse etc.) operate to isolate the faulty conductor from the rest of the system. This point is illustrated in Figure 10.1.

Figure 10.1 shows a 3-phase, star-connected system with neutral earthed. Suppose a single line to ground fault occurs in line R at point F. This will cause the current to flow through ground path as shown in Figure1. Note that current f lows from R phase to earth, then to neutral point N and back to R-phase. Since the impedance of the current path is low, a large current flow through this path. This large current will blow the fuse in R-phase and isolate the faulty line R. This will protect the system from the harmful effects of the fault. One important feature of grounded neutral is that the potential difference between the live conductor and ground will not exceed the phase voltage of the system i.e., it will remain nearly constant.

Introduction

In normal working condition of electrical network, the current flows through the network is within the rated limit. If a fault occurs in the network mainly phase to phase short circuit fault or phase to ground fault, the network current crosses the rated limits. This high current may have a very high thermal effect which will cause permanent damage to the valuable pieces of equipment connected to the electrical network. So this high fault current should be interrupted as fast as possible. This is what an electrical fuse does. A fuse is a part of the circuit which consists of a conductor which melts easily and breaks the connection when current exceeds the predetermined value. An electrical fuse is the weakest part of an electrical circuit which breaks when more than predetermined current flows through it.

Introduction

The insulating material (may be fluid or air) used in circuit breaker should serve two important functions. They are written as follows:

1. It should provide sufficient insulation between the contacts when circuit breaker opens.

2. It should extinguish the arc occurring between the contacts when circuit breaker opens.

The second point needs more explanation. To understand this point let us consider a situation if there is some fault or short circuit in the system, the relay provides desired signals to the circuit breaker so as to prevent system from ongoing fault. Now when circuit breaker opens its contacts, due to this an arc is drawn. The arc is interrupted by suitable insulator and technique.

Methods of Arc Interruption

Introduction

A generator is subjected to electrical stresses imposed on the insulation of the machine, mechanical forces acting on the various parts of the machine, and temperature rise. These are the main factors which make protection necessary for the generator or alternator. Even when properly used, a machine in its perfect running condition does not only maintain its specified rated performance for many years, but it does also repeatedly withstand certain excess of overload.

Preventive measures must be taken against overloads and abnormal conditions of the machine so that it can serve safely. Even ensuring an efficient design, construction, operation, and preventive means of protection – the risk of a fault cannot be completely eliminated from any machine. The devices used in generator protection, ensure that when a fault arises, it is eliminated as quickly as possible.

Introduction

Dr. C.L. Fortescue presented a paper in 1918 in which he proved that a system of several vectors or quantities may be resolved into equal different symmetrical groups or systems.

The method of symmetrical components is a general one applicable to any polyphase system.

Because of the widespread use of 3-phase systems and the greater familiarity which electrical engineers have with them, symmetrical component equations will be developed for three phases.

In the Analysis of Unsymmetrical Faults, the following assumptions will be made:

1. The generated emf system is of positive sequence only.

2. No current flows in the network other than due to fault i.e. load currents are neglected.

3. The impedance of the fault is zero.

4. Phase R shall be taken as the reference phase.

Introduction

Dr. C.L. Fortescue presented a paper in 1918 in which he proved that a system of several vectors or quantities may be resolved into equal different symmetrical groups or systems. The method of symmetrical components is a general one applicable to any poly-phase system. Because of the widespread use of 3-phase systems and the greater familiarity which electrical engineers have with them, symmetrical component equations will be developed for three phases.

The useful expression showing relationship between unsymmetrical and symmetrical component:

Introduction

The Over-head insulator for overhead lines provides insulation to the electrical conductor. It is connected to the cross arm of the supporting structure and the electrical conductor passes through the clamp (insulator). It is mainly made of either glazed porcelain (Silica 20% + Feldspar 30% + Clay 50%) or toughened glass. The porcelain must be free from any defect. It should be vitrified because the presence of pore or air will lower down its dielectric strength. Any captured air impurity will also reduce the dielectric strength of the porcelain. Therefore, it is highly desirable that the insulators should be air free and resistant to the entrance of liquids/gases. It is desirable not to allow porcelain to come in direct contact with a hard metal screw thread. Therefore, cement is used between metal and the porcelain.

Introduction

For the analysis of electrical power system, different values are required, thus, per unit system provides the value for voltage, current, power, impendence, and admittance. The Per Unit System also makes the calculation easier as all the values are taken in the same unit. The per-unit system is mainly used in the circuit where variation in voltage occurs. The per-unit value of any quantity is defined as the ratio of actual value in any unit to the base or reference value in the same unit. Any quantity is converted into per unit quantity by dividing the numeral value by the chosen base value of the same dimension. The per-unit value is dimensionless.

Short Transmission Line

A short transmission line is defined as a transmission line with an effective length less than 80 km (50 miles), or with a voltage less than 69 kV. Unlike medium transmission lines and long transmission lines, the line charging current is negligible, and hence the shunt capacitance can be ignored.

For short length, the shunt capacitance of this type of line is neglected and other parameters like electrical resistance and inductor of these short lines are lumped, hence the equivalent circuit is represented as given below. Let’s draw the vector diagram for this equivalent circuit, taking receiving end current Ir as reference. The sending end and receiving end voltages make angle with that reference receiving end current, of φs and φr , respectively.

 

Introduction

Electrical Engineering generally uses a consistent, structured approach to the solving of various practical problems. An acceptable problem-solving approach and method can be defined, although variations can be seen in specific problems. Problems need to be approached methodically, applying an algorithm by which engineer arrives at an acceptable solution.

Problem-Solving Process in Engineering: (i) Define the engineering problem (ii) Create a mathematical model (iii) Develop a computational method for solving the problem (iv) Implement the computational method (v) Test and assess the solution.

7.1 Introduction

Okra is a remunerative vegetable crop for the tropical and subtropical regions of the world. Its fresh fruits are important vegetable in India, Brazil, West Africa and many other countries. For year-round consumption sun dried (Africa, India), and frozen and sterilized (USA) fruits are processed from fresh fruits. Tender green fruits are cooked in curry and also used in soups. The root and stem are useful for clearing cane juice in preparation of jaggery. Its ripe seeds are roasted, ground and used as a substitute for coffee in Turkey. Matured fruits and stems containing crude fibre are used in the paper industry. Okra is rich in vitamins, calcium, potassium and other minerals. A 100g consumable unripe okra fruits contain 10.4g dry matter, 3,100 calorie energy, 1.8g protein, 90mg calcium, 1.0mg iron, 0.1mg carotene, 0.07mg thiamin, 0.08mg riboflavin, 0.08mg niacin and 18 mg vitamin C. The dry seeds contain 13-22% edible oil and 20-24% protein. The seed cake is also used as an animal feed. Okra has high iodine content and it has ability to control goiter. Ratoon cropping can also be done in okra.

19.1 Introduction

Roselle is a perennial shrub but grown as an annual. In the seventeenth century, the vegetable types were introduced to India and the United States of America. It is locally known as Mesta or Meshta in the Indian subcontinent. It is one of the important fibre crops, which stands next to jute in production. In India, mesta is grown in larger parts covering areas from Karnataka to Tripura including Maharashtra, Andhra Pradesh, West Bengal, Bihar, Odisha and Meghalaya. However, Andhra Pradesh has maximum area under mesta in the country. In many tropical regions, it is a popular vegetable, which is cultivated for its leaves, stems, seeds and calyces. Tender young leaves are eaten as a vegetable and the red calyces surrounding the fruit can be used to prepare non-alcoholic beverages and as colouring reagent for jelly, jam, and beverages. The stem is utilised for extraction of fibre. The plant stalks are used in making paper pulp, structural boards, as a blend for wood pulp and thatching huts. The leaves are a source of mucilage used in pharmaceuticals and cosmetics. Culinary cultivars are many branched, bushy and generally 1-2 m tall.

18.1 Introduction

Sorrel is a perennial herb, which is found in grassland habitats throughout Europe from the northern Mediterranean coast to the north of Scandinavia and in parts of Central Asia. It is of two types such as Garden sorrel that is a native of Europe and south western Asia and French sorrel that is originated in the mountains of southern France and the southern and central regions of Europe and south-west Asia. The name sorrel is derived from the Germanic word, Sur and the old French word Surele, both meaning sour. It is primarily used as a culinary herb for its leaves, which are used in salads too. The leaf of this plant resembles that of spinach and have a lemony lettuce flavour and the plant is well known for strong acidity in Europe and the United States. Sorrel is a rich source of potassium, iron and vitamins A, B1 and C. The flavour of sorrel leaves is mainly due to oxalic acid, which is harmless when consumed in small amount. Owing to high level of vitamin C content, it was rightly believed to protect against scurvy disease. It is a dioecious plant, that bears unisexual flowers, as the male and female flowers appear on different plants. When the plant flowers, they look very attractive and are often used as an ornamental plant.

17.1 Introduction

Basella is a short-lived but productive leafy vegetable of the tropics. Its resistance to pests and diseases makes it very promising for small-scale production in home and market gardens. The plant is a climbing vine with thick fleshy stem and leaves. They are chopped and cooked as vegetables and has ornamental value too. Its leaves are rich source of vitamin A (3250 IU/100g), protein (1.2%) and rich source of iron (1.4mg/100g). The succulent leaves with petioles and tender leaves are cooked as vegetables. The plant is a climbing vine with thick fleshy stem and leaves. It was cultivated since long in South-East Asia and China, and is now widespread throughout tropical Asia, Africa and America. It is a popular vegetable in Malaysia and the Philippines. The colouring matter present in the red cultivar is reported to have been used in China as a red dye for official seals, as ink. These are used to allay fever and as a mild laxative for pregnant women. A decoction from the plant is used to alleviate labour pains. Boiled leaves are used as a poultice. Flower spikes are sold as vegetable in northern Thailand markets. Flowers have been reported as an antidote to poisons. Fruit juice is used as eye-drops in the treatment of conjunctivitis. Cooked roots are used to cure diarrhoea, while cooked leaves and stems are used as a laxative. The red types of Ceylon spinach are very popular ornamentals and are grown as a pot plant in Europe.

16.1 Introduction

Portulaca is an annual potherb, but may be perennial in the tropics. In many parts of the world, it is still regarded as a weed with nutritional potential. Its young stems and leaves are succulent and edible with a slightly acidic and salty taste. Stems are glabrous, fleshy, purplish-red to green, arising from a taproot, often prostrate, forming mats. It is described as a power food of the future because of its high nutritive and antioxidant properties. It contains more omega-3 fatty acids (300 to 400 mg/100 g of fresh leaves) than any other leafy vegetable plant. Succulent leaves and stem also contain dietary minerals, such as calcium, phosphorus, iron and potassium, as well as vitamins A, C and E and some amount of vitamin B and carotenoids. It has been recommended as a cholesterol lowering agent and as a therapy for arteriosclerosis. Generally, roots and leaves contain more iron and manganese than stems. Due to oxalic acid and nitrate content, excessive consumption of purslane is not recommended. The cultivated form of Purslane, i.e., Portulaca oleracea (garden or green purslane) and Portulaca sativa (yellow leaves, less hardy than the green purslane but possessing the same qualities), is hexaploid. Purslane is a succulent and well-branched herb, leaves are spirally arranged, flowers are yellow, stamens 7-10, style with arms, fruit ovoid, capsule, seeds numerous, tiny and black in colour.

15.1 Introduction

Curry leaf is an important perennial tree vegetable cum spice crop of India mostly used in South Indian culinary preparations for flavouring food stuff. It is an under exploited crop. The leaves have slightly pungent, bitter and feebly acidic taste and they retain their flavour and other qualities even after drying. Curry leaf is used in many of the Indian Ayurvedic and Unani prescriptions. It has many industrial values and medicinal uses. Its leaves, roots and bark are credited with tonic, stomachic and carminative properties. Leaves are reported to cure piles and allay heat of body. The green leaves are said to be eaten raw for treatment of dysentery. External application of pulped bark and root is reported to relive eruptions and bites of poisonous animals. An injection of toasted leaves is used to stop vomiting. The tribal people of India use its ground bark to rub on the bitten Part As a snake bite remedy. The powdered leaves are also used to aid in healing of fresh cuts. The dried curry leaf powder is also a good spice powder for use in the food stuff preparation and is exported. Fresh leaves on a steam distillation under high pressure yield 2.6 % (curry leaf oil) volatile oil which is used as fixative for heavy type of soap and perfume. Rectified leaf oil is deep yellow in colour with a strong spicy odour and pungent clove like taste. A volatile oil, a crystalline glucoside ‘Koenigin’ from the leaves and ‘Murayam’ from the flowers are industrial products. Curry leaf is grown on large scale in West Bengal, Assam, Deccan plateau, Western Ghats, Tamil Nadu, Karnataka and Kerala. It is cultivated in Coimbatore, Salem and Tiruchirappalli districts of Tamil Nadu on a commercial scale.

14.1 Introduction

Drumstick is one of the most popular perennial tree vegetables in the south Indian households and known as miracle tree. This perennial vegetable survives for several years and goes on yielding vegetables without much care and attention, and is planted on the side of the kitchen garden without much interference with tillage operations of other annual crops. The fruits, leaves and flowers are used in culinary preparation. Immature fruits are cut into pieces and used in several culinary dishes. Fruits are rich in Vitamin C, carotene, Phosphorus and minerals like Mg, K, S, Cl etc. Tender leaves and flowers are comparable to that of Colocasia in vitamins and minerals. Drumstick leaves contain high amount of vitamin A (four times more than carrot), vitamin C (seven times more than orange), protein (5-10%), calcium (four times more than milk) and potassium (three times more than banana).The roots of the plant are used for seasoning pickles. Its roots are a good substitute for Horse Radish so called as Horse radish tree. It is highly valued for the distinct and appealing flavour for its tender fruits. They are rich source of protein, minerals and vitamins. Seeds contain an oil called ben or behen oil which has been much used for illumination, soap industry and highly priced for lubricating watches, computers, delicate machinery and so known as Ben oil tree. Seeds contain 38-40% of non-drying oil which is clear and odourless, that never becoming rancid. The oil contains high levels of unsaturated fatty acids, especially oleic acid up to 67.8%. It is edible and useful in the manufacture of perfumes and hair dressing. The press cake remaining after oil extraction is high in saponin, not edible, but utilized as manure. The oil cake is a water coagulant and used for purifying effluent water. It is used as organic substitute for water purifying chemicals such as aluminium sulphate. Wood yields blue dye and coarse fibre. The plant is used for treatment of rheumatism and as cardiac and circulating system stimulants. It has fragile and cory stem. The trunk is gaining importance as a raw material for paper making. The gum of stem has medicinal properties. The leaves are usually tri-pinnate with elliptic leaflets. Seeds are trigonous with wings on angles. Flowers are produced on current seasons growth on large and erect panicles or monocladial cymes. Flowers are yellowish creamy white and sweet smelling. It is a cross-pollinated crop. Pollinator is carpenter bees, bumble bee, honey bee and flee beetle. Flowering mostly varies from place to place and is greatly influenced by rain, temperature, humidity, wind, soil moisture and soil temperature etc. Peak period of flowering in central parts of India and Kerala is December-January while in southern part it is February-March and July-August with maximum flowering in February-March. Fruits take 60 days for horticultural maturity during rainy season while 30 days in summer.

13.0 Introduction

Cucurbits belong to the family Cucurbitaceae, commonly known as the melon or gourd family. The term cucurbits was coined by Dr Bailey. From nutritional point of view, cucurbit seeds are valued for their high oil and protein contents. Seed proteins and methionine of cucurbits are higher than legumes. Vegetatively propagated cucurbits are pointed gourd, ivy gourd and chow-chow. Long day of 16 hours and high temperature result in maleness. Short day of 9 hours results in femaleness. They are widely distributed in the tropics and warm temperate regions of south, southeast and East Asia, Africa including Madagascar, and central and south America. Cucurbitaceae family is represented by about 117 genera and 825 species. The most common uses of cucurbits are as vegetables and fruits. They are valuable sources of vitamins and minerals. The important cucurbits that are cultivated commercially are cucumber, watermelon, musk melon, long melon, round melon, bottle gourd, bitter gourd, ash gourd, ridge gourd, sponge gourd, pumpkin, squash, snake gourd, pointed gourd, spine gourd, ivy gourd and chow-chow etc. Cucurbits are used as vegetable, salads, dessert and pickle, and for making of sweets.