I am extremely thankful & indebted to the numerous BHEL Engineers and technical staffs who provided vital information about the functioning of their respective departments thus helping me to gain an overall idea about the working of organization. I am highly thankful for the support & guidance of each of them. I am extremely thankful to Dr. DHRUVA BHARGAVA, GENERAL MANAGER (HRD) for providing me the opportunity to undergo this training and to work on my project. I also express my thanks to all the members of HRD for their help & cooperation. I am highly indebted and thankful to my project guide, Mr. LALIT KUMAR and for giving me their valuable time and helping me to grasp the various concepts of locomotive manufacturing and their various parts and assembly processes and testing. I would also like to thank all other members of Locomotive Manufacturing and Testing Dept. for providing enough support and cooperation.
Himanshu Rathore (1109732052)
TABLE OF CONTENTS Page No
TABLE OF CONTENTS
1. BHEL – An Overview Company Portfolio 1.1 About BHEL. 2 1.2 Company profile. 3 1.3 Growth of BHEL. 5 1.4 Activity Profile of BHEL. 6 1.5 Overseas Buisness Project Portfolio 2. BHEL Jhansi at a Glance 2.1 Location of plant. 11 2.2 Modern Machinery in BHEL Jhansi 2.3 Product Profile of BHEL Jhansi Unit 3. BHEL JHANSI UNIT – Sectional Distribution 3.1 4. Electrical Analysis of Locomotive (WAG-7) 4.1. asdfasf
5. Conclusion. 57 6. Bibliography. 58
BHEL – An Overview
COMPANY PORTFOLIO 5
1.1 About BHEL India’s largest power company, NTPC was set up in 1975 to accelerate power development in India. NTPC is emerging as a diversified power major with presence in the entire value chain of the power generation, which is the mainstay of the company, NTPC has already ventured into consultancy, power trading, ash utilization and coal mining. NTPC has ranked 337th in the ‘2012, Forbes Global 2000’ranking of the world’s biggest companies. NTPC become a MAHARATNA company in May, 2010, one of the only four companies to be awarded this status. The total installed capacity of the company is 39174 MW (including JVs) with 16 coal based and 7 gas based station, located across the country. In addition under JVs, 7 stations are coal based & another station uses naphtha/LNG as fuel. The company has set a target to have an installed power generating capacity of 1, 28,000 MW by the year 2032.The capacity will have a diversified fuel mix comprising 56% coal, 16% gas ,11% nuclear and 17% Renewable energy sources (RES) including hydro. By 2032, no fossil fuel based generation capacity shall make up nearly 28% of NTPC’s portfolio. NTPC has been operating its plants at high efficiency levels. Although the company has 17.75 % of the total national capacity it contributes 27.40% of total power generation due to its forces on high efficiency. NTPC has been awarded No.1, Best Workplace in India among large organizations and the best PSU for the year 2010, by the great places to Work Institute, India chapter in collaboration with The Economic Times. The concept of corporate social responsibility is deeply ingrained in NTPC’s culture. It is emerging as an “Integrated Power Major “with a significant presence in the entire value chain of power generation business. ‘People before PLF (Plant Load Factor)’ is the guiding philosophy behind the entire gamut of policies at NTPC.
1.2 COMPANY PROFILE
National Thermal Power Corporation Ltd.
State –Owned enterprise public company
A Maharatna Company
Traded as: BSE: 532555 NSE: NTPC BSE: SENSEX Constituent Industry:
Headquarters: New Delhi, India Key people: Arup Roy Choudhury (Chairman & M.D) Products:
Engineering Power and services
Electrical generation and distribution, Natural gas exploration, production, Transportation & Distribution
Revenue: Net Income:
620.53 billion (US$11.73 billion in year 2011-12) 92.23 billion (US$1.74 billion in year 2011-12)
Employees: approx.26000 (till 2012) Website: www.ntpc.co.in
Vision: “A World Class Engineering Enterprise Committed to Enhancing Stakeholder Value”.
Mission: “To be an Indian Multinational Engineering Enterprise providing Total Business Solutions through Quality Products, Systems and Services in the fields of Energy, Industry, Transportation, Infrastructure and other potential areas”. Core Values:
Zeal to Excel and Zest for Change. Integrity and Fairness in all Matters. Respect for Dignity and Potential of Individuals. Strict Adherence to Commitments. Ensure Speed of Response. Foster Learning, Creativity and Teamwork. Loyalty and Pride in the Company
1.3 GROWTH OF BHEL
1.4 ACTIVITY PROFILE OF BHEL Power Sector Projects
Thermal sets and Auxiliaries. Steam generators and Auxiliaries. Industrial fans. Electrostatic precipitators. Air pre heaters. Nuclear power equipments. Hydro sets and Auxiliaries. Motors. Transformers. Rectifiers. Pumps. Heat Exchangers. Capacitors. Porcelain/Ceramics insulators. Seamless steel tubes. Casting and forging.
Turnkey power station. Data acquisition Systems. Power systems. HVDC Commissioning systems. Modernization and Rehabilitation.
Diesel Electric generators. AC/DC locomotives. DC locomotives and loco shunters. Traction system for railways. Electric trolley buses.
Boilers. T.G. sets. Power devices. Solar Cells. Photo Voltaic cells. Gas Turbines. Compressors. 10
Drive Turbines. Wind mills. Control systems for electric devices.
1.5 OVERSEAS BUISNESS
BHEL has, over the years, established its references in 76 countries across all the six continents of the world. These references encompass almost the entire range of BHEL products and services, covering thermal, hydro and gas-based turnkey power projects, substation projects and rehabilitation projects, besides a wide variety of products like; transformers, compressors, valves and oil field equipment, electrostatic precipitators, photovoltaic equipment, insulators, heat exchangers, switchgear, castings and forgings, etc. Some of the major successes achieved by BHEL have been in gas-based power projects in Oman, Libya, Malaysia, UAE, Saudi Arabia, Iraq, Bangladesh, Sri Lanka, China, Kazakhstan, Belarus, Yemen; thermal power projects in Cyprus, Malta, Libya, Egypt, Indonesia, Thailand, Malaysia, Sudan, Syria, Ethiopia, Senegal, New Caledonia, Ukraine; hydro power plants in New Zealand, Malaysia, Azerbaijan, Bhutan, Nepal, Taiwan, Tajikistan, Vietnam, Rwanda, Thailand, Afghanistan, Democratic Republic of Congo, Burundi; and substation projects & equipment in various countries. Execution of these overseas projects has also provided BHEL the experience of working with world renowned consulting organizations and inspection agencies. The company has been successful in meeting demanding requirements of international markets, in terms of complexity of work as well as technological, quality and other requirements viz. HSE requirements, financing packages and associated O&M services, to name a few. The company is taking a number of strategic business initiatives to fuel further growth in overseas business. This includes firmly establishing itself in target export markets, positioning BHEL as a regular EPC contractor in the global market both in utility and IPP segments and exploring various opportunities for setting up overseas joint ventures etc. 11
1st Generation Units Bhopal
: Heavy Electrical Plant.
Haridwar : Heavy Electrical Equipment Plant. Hyderabad: Heavy Electrical Power Equipment Plant.
2nd Generation Units Tiruchy
High Pressure Boiler Plant.
: Transformer and Locomotive Plant.
Haridwar : Central Foundry and Forge Plant. Tiruchy
Seamless Steel Tube Plant.
Units through Acquisition & Merger Bangalore : Electronics Division Electro Porcelain Division.
New Manufacturing Units Ranipet
Boiler Auxiliaries Plant.
Govindwal : Industrial Valve Plant. Rudrapur
Component and Fabrication Plant.
Energy Systems Division
BHEL Jhansi at a Glance
2.1 HISTORY OF BHEL JHANSI
By the end of 5th five-year plan, it was envisaged by the planning commission
that the demand for power transformer would rise in the coming years. Anticipating the country’s requirement BHEL decided to set up a new plant, which would manufacture power and other types of transformers in addition to
the capacity available in BHEL Bhopal. The Bhopal plant was engaged in manufacturing transformers of large ratings and Jhansi unit would concentrate on power transformer upto 50 KVA, 132 KV class and other 77transformers like Instrument Transformers, Traction
transformers for railway etc. This unit of Jhansi was established around 14 km from the city on the N.H. No 26 on Jhansi Lalitpur road. It is called second-generation plant of BHEL set up in 1974 at an estimated cost of Rs 16.22 crores inclusive of Rs 2.1 crores for township. Its foundation was laid by late Mrs. Indira Gandhi the prime minister on 9th Jan. 1974. The commercial production of the unit began in 1976-77 with an output of Rs 53 lacs since then there has been no looking back for BHEL
Jhansi. The plant of BHEL is equipped with most modern manufacturing processing and testing facilities for the manufacture of power, special transformer and instrument transformer, Diesel shunting locomotives and AC/DC locomotives. The layout of the plant is well streamlined to enable smooth material flow from the raw material stages to the finished goods. All the feeder bays have been laid perpendicular to the main assembly bay and in each feeder bay raw material smoothly gets converted to sub assemblies, which after inspection are sent to
main assembly bay. The raw material that are produced for manufacture are used only after thorough material testing in the testing lab and with strict quality checks at various stages of productions. This unit of BHEL is basically engaged in the production and manufacturing of various types of transformers and capacities 13
with the growing competition in the transformer section, in 1985-86 it under took the re-powering of DESL, but it took the complete year for the manufacturing to begin. In 1987-88, BHEL has progressed a step further in under taking the production of AC locomotives, and subsequently it manufacturing AC/DC locomotives also.
2.2 LOCATION OF BHEL JHANSI
Spread over 2,465 acres of land, the Dadri power station is situated on the Dadri Dhaulana road [10 km. off Dadri G.T. road, and 12 km. off the National Highway # 24] . The route from New Delhi to NCPS is 60 km. long and is about 25 km. from Ghaziabad.
Address National Thermal Power Corporation Limited P.O. Vidyut Nagar, Pin Code: 201 008 District: Gautam Budh Nagar State: Uttar Pradesh
2.3 MODERN MACHINERY IN BHEL JHANSI
CNC CROPPING LINE MACHINE VAPOR PHASE DRYING SYSTEM COMPUTER ICM 6040 AND 6080 AND IRISII 40/20 WITH GRAPHIC FACILITIES BOGIE FRAME MACHINE CENTER CNC AXLE TURNING LATHE FACING AND CENTERING MACHINE WHEEL FORCING PRESS CNC PIPE BENDING MACHINE
2.4 PRODUCT PROFILE OF BHEL JHANSI UNIT 14
upto 400 kV/315 MVA
upto 132 KV/120 kA
upto 33 kV/60 MVA
Transformer for ESP
upto 95 KVA/1400mA
Traction Transformers Single Phase Freight Loco Three Phase Freight Loco
upto 25 kV/5400kVA upto 25 kV/7475kVA
Transformer for ACEMU upto 25 kV/1550 kVA
upto 25 kV/1550 Kva
Cast Resin Dry Type Transformer upto 33 kV/15 MVA
upto 33 kV/15 MVA
Diesel electric locomotives
3. BHEL JHANSI UNIT Sectional Distribution
3.1 SECTIONS OF BHEL JHANSI UNIT BHEL has many departments, while production and administrative departments are separate. Broadly speaking BHEL has two-production categories1. Transformer section. 2. Loco section. 3. Bus Duct section 2.6 TRANSFORMER SECTION 2.6.1 TRANSFORMER COMMERCIAL (TRC) The objective of the department is interaction with the customers. It brings out tenders and notices and also responds to them. It is this department that bags contracts of building transformers. After delivery regarding faults, this department does failures and maintenance. All such snags are reported to them and they forward the information to the concerning department. The main work of the TRC is classified as: 1. Tenders and notices. 2. Interaction with design department. 3. Place of the work. 4. Approximate cost of the work. 5. Earnest money. 6. The place and time where contract documents can be seen. 7. The place and time where tender documents can be obtained. 8. The time up to which the tender documents will be sold.
2.6.2 TRANSFORMER ENGINEERING (TRE) 16
The transformer manufactured in BHEL Jhansi range from 10 MVA to 315 MVA and up to 400 KV. The various transformer manufactured in this unit are:-
Figure 2.1 POWER TRANSFORMER Power transformer a) Generator transformer b) System transformer. c) Auto transformer.
Special transformer. a) Freight loco transformer. b) ESP transformer. c) Instrument transformer. 17
d) Dry type transformer. All above types are oil cooled except dry type, which are air-cooled. The generated voltages at the power station are 6.9 KV, 11 KV and 13.8 KV but due to certain advantages like economical generation 11 KV is the most widely used. For this voltage needs to be stepped up. Transmission at high voltage is desirable because it results in lesser losses, needs thinner wire and hence is economical. If the current is kept high the copper losses become very high but iron losses are practically constant. In certain cases the required voltage may be less than the output voltage, so in order to obtain it we require a tapping circuit. The output voltage may have a certain percentage variation, which may be tapped in 4 or 6 equal steps. The type of tap changer depends on the application of the transformer, where a continuous power supply is not required an Off Circuit Tap Changer (OCTC) may be used and where a continuous power supply is a must e.g. at a substation in cities etc. on Load Tap Changer (OLTC) is used.
2.6.3TRANSFORMER MANUFACTURING (TRM): The manufacturing of transformer is carried out in a systematic manner with work assigned to the following sections to smoothly carry out the job within the promised period.
Fabrication is nothing but production. It comprises of 3 bays i.e., Bay0, Bay1 &Bay 2.
It is the preparation shop while the other two bays form the assembly shop. 18
This section has the following machines: 1. Planner machine – To reduce thickness 2.
Shearing machine 3. CNC / ANC Flame Cutting machine – To cut complicated shaft items using Oxy-Acetylene flame
4. Bending machine 5. Rolling machine 6. Flattening machine 7. Drilling machine 8. Nibbling machine 9. Pantograph flame cutting machine
It is an assembly shop where different parts of tank come from bay 0.Here welding processes are used for assembly, after which a rough surface is obtained Grinder operating at 1200 rpm is used to eliminate the roughness. 2.6.3.1.3 BAY-2
It is an assembly shop dealing with making different objects mentioned below:1-Tank assembly
5-cross feed assembly
2-Tank cover assembly
6-core clamp assembly
3-End Frame assembly
7-pin and pad assembly
Before assembly, short blasting (firing of small materials i.e., acid pickting) is done on different parts of jobs to clean the surface before painting. After assembly some tests are done known as NON DESTRUCTIVE TEST 1. Ultrasonic test: to detect the welding fault on the CRO at the fault place high amplitude waves are obtained. 2. Die Penetration test: Red solution is put at the welding and then cleaned. After some time white solution is put. Appearance of a red spot indicates a fault at the welding. 3. Magnetic crack detection: Magnetic field is created and then iron powder is put at the welding. Sticking of the iron powder in the welding indicated a fault. 4. X-Ray Test: It is same as human testing and the fault is seen in X-ray film. 2.6.3.2 BAY-3 Here are basically three sections in the bay: 1. Machine section 2. Copper section 3. Tooling section
2.6.3.2.1 MACHINE SECTION: The operations to form small components of power and traction transformer are done in this section. The shop consist of following machines:
CENTRAL LATHE: it consist one tailstock, headstock, lower part of tailstock is fixed and tail stock spindle is moving. On this machine facing, turning and threading is done TURRET LATHE: its function is same as central lathe but it is used for mass production. Here turret head is used in presence of tailstock because turret head contains many tailstocks around six. CAPSTAN LATHE: It is belt drive. RADIAL ARM DRILLING MACHINE: It is used for drilling and boring. HORIZONTAL BORING MACHINE: It is computerized and used for making bore, facing etc. MILLING MACHINE:a) Horizontal milling machine: It is used for making gear and cutting operations. b) Vertical milling machine: By the machine facing cutting, and T-slot cutting is done
2.6.3.2.2 COPPER SECTION: All the processes related to copper are done here.
TUBE SLITTING MACHINE: This machine is developed here and is used for cutting the tube along its length and across its diameter. Its blade thickness is 3mm. SHEARING MACHINE: It is operated hydraulically and its blade has V-shape and a thickness of 15mm DIE AND PUNCHING MACHINE: It is also hydraulically operated and has a die and punch for making holes. HYDRAULIC BENDING MACHINE: It is used for bending the job upto 90°.
SHEARING MACHINE: It is fully mechanical and is used to cut the job along its width. FLY PRESS MACHINE: It is used to press the job. It is operated mechanically by a wheel, which is on the top of the machine. BEND SAW MACHINE: This machine is used for cutting job having small thickness. It has a circularly operated blade, around 5.1 mtr long. WATER COOLED BRAZING MACHINE: It contains two carbon brushes. The sheet is put along with a sulfas sheet and the carbon brushes are heated. A Lap Joint is formed between the sheets as the sulfas sheet melts. LINCING BELT MACHINE: It creates a smooth surface. HYDRAULIC PRESS MACHINE: To press the job. SOLDER POT MACHINE: It has a pot that contains solder. Solder has a composition of 60% Zn and 40% Pb.
2.6.3.2.3 TOOLING SECTION: In this section the servicing of tools is done.
BLADE SHARP MACHINE: It sharpens the blade using a circular diamond cutter. Blade of CNC cropping line machine is sharpened here. MINI SURFACE GRINDER MACHINE: It serves grinding purposes. It has a grinding wheel made of “Aluminum Oxide”. TOOL & SURFACE GRINDING MACHINE: This is specially used to grind the tools used in Bay 7. DRILL GRINDING MACHINE: To grind the drills.
This is the winding section. TYPES OF WINDING : 1. Reverse section winding. 2. Helical winding 3. Spiral winding 4. Interleaved winding 5. Half sectional winding
There are four TYPES OF COIL fixed in a transformer, they are : 1. Low voltage coil (LV) 2. High voltage coil (HV) 3. Tertiary coil 4. Tap coil
The type of winding depends upon job requirement. Also, the width and thickness of the conductors are designed particulars and are decided by design department. Conductors used for winding is in the form of very long strips wound on a spool, the conductor is covered by cellulose paper for insulation. 23
For winding first the mould of diameter equal to inner dia meter of required coil is made .The specification of coil are given in drawing. The diameter of mould is adjustable as its body is made up of wooden sections that interlock with each other. This interlocking can be increased or decreased to adjust the inner diameter of coil. The moulds are of following types.1. Belly types 2.
It is core and punch section. The lamination used in power, dry, ESP transformer etc for making core is cut in this section. CRGO (cold rolled grain oriented) silicon steel is used for lamination, which is imported in India from Japan, U.K. Germany. It is available in 0.27 and 0.28 mm thick sheets, 1mt wide and measured in Kg .The sheet s are coated with very thin layer of insulating material called “carlites”. For the purpose of cutting and punching the core three machines are installed in shop
1. SLITTING MACHINE: It is used to cut CRGO sheets in different width. It has a circular cutter whose position can be changed as per the requirement. 2. CNC CROPPING LINE PNEUMATIC: It contains only one blade, which can rotate 90° about the sheet .It is operated pneumatically. 3. CNC CROPPING LINE HYDRAULIC: It is also used to cut the CRGO sheet. It contains two blades, one is fixed and the other rotates 90° above the sheet. It is operated hydraulically .M4 quality sheet 0.23-0.33 mm thickness is used
Single-phase traction transformer for AC locomotives is assembled in this section. These Freight locomotive transformers are used where there is frequent change in speed. In this bay core winding and all the assembly and testing of traction transformer is done. Three-phase transformers for ACEMU are also manufactured in this section. The supply lines for this transformer is of 25 KV and power of the transformer is6500 KVA. The tap changer of rectifier transformer is also assembled in this bay. Rectified transformer is used in big furnace like the thermal power stations / plants ( TPP).
This is the insulation shop. Various types of insulations are
1- AWWW: All Wood Water Washed press paper. The paper is 0.2-0.5mm thick cellulose paper and is wound on the conductors for insulation. 2-PRE-COMPRESSED BOARD: This is widely used for general insulation & separation of conductors in the forms of blocks. 3-PRESS BOARD: This is used for separation of coils e.g. L.V. from H.V. It is up to 38 mm thick. 4-UDEL: UnDemnified Electrical Laminated wood or Permawood This is special type of plywood made for insulation purposes.
5-FIBRE GLASS: This is a resin material and is used in fire pron areas. 6-BAKELLITE 7-GASKET-It is used for protection against leakage.
8-SILICON RUBBER SHEET-It is used for dry type transformer.
The machines used for shaping the insulation material are 1-Cylindrical machines 2-Circle cutting machine 3 Scarping machines 26
4-Punching press machine 5-Drilling machine 6-Guilletin machines 7-Bench saw (spl for OD) 8-Jig saw (spl for ID) 9-Circular saw 10-Linesin machines 2.6.3.7 BAY 8 It is the instrument transformer and ESP transformer manufacturing section.
2.6.3.7.1 INSTRUMENT TRANSFORMER -
These are used for measurement. Actual measurement is done by measuring instruments but these transformers serve the purpose of stepping down the voltage to protect the measuring instrument. They are used in AC system for measurement of current voltage and energy and can also be used for measuring power factor, frequency and for indication of synchronism. They find application in protection of power system and for the operation of over voltage, over current, earth fault and various other types of relays. They are of two types. 1-Current transformer (CT) 2-Voltage transformer (VT)
2.6.3.7.1.1 CURENT TRANSFORMERIt is a step down transformer. High current is not directly measured by the CT but is stepped down to lower measurable voltages. 27
BODY: The main body is a bushing, which houses the winding and also acts as an insulator.
The CT has a bottom and top chamber.
The top chamber is a cylindrical tank of mild steel. It has terminals for connection of HV coils. It also has a glass window to indicate the oil level.
Below the top chamber is the bushing made of porcelain. It has several folds or “rain sheds” to provide a specific electric field distribution and long leakage path. Some bushings are cylindrical while modern ones are conical as amount of oil porcelain used is reduced without any undesirable defect.
Bottom chamber houses the secondary winding. There is also connection box to which the connection of the low voltage (LV) coil is made.
WINDINGS: The primary winding consists of hollow copper/aluminum pipe bent in form of a ‘U’. Aluminum is used for low rating. For higher rating a set of wires is passed through the pipe. For still higher ratings, a copper pipe is used and for highest rating copper pipe with copper wires passing through it is used. This arrangement depends on the current carrying capacity. The bent portion of primary as in the bottom chamber where as the free end is the top chamber. The straight portion lies inside the bushing. The primary is wound with crepe paper insulation. The thickness of the insulation goes in increasing as we go downwards in the bottom chamber. The free ends are provided with ‘ferrules’, which are, small hollow cylinders through which wires can pass connection to the primary are made through these ferrules. The secondary is divided in a number of coils for different set of tapings. Connections are different tapings are made in connection box. Each coil has an annular core of CRGO (silicon steel). The wire use is insulated copper wire. The winding may be 28
done both manually and by machine. After winding the coils are covered with paper tape insulation. The coils are then slipped into both the legs of the primary winding and connections are made in connection box for different tapping. 2.6.3.7.1.2 VOLTAGE TRANSFORMERS:
This is also a stepped down transformer. The outer construction is same as that of the CT that is this also has a top chamber, bushing and a bottom chamber. The difference is only in the winding.
WINDINGS: The primary winding is of the thick wire having a few turns. The winding is heavily insulated with paper insulation. It has a hollow cylinder passing centrally through it, which houses the secondary winding. The clean and painted with either enamel or epoxy paint. The customer gives the choice of paint. Epoxy paint is generally used in chemical plants and seashore installation. Terminals are then mark and ratings and diagram plate is fixed. The job is then sent to the shipping department, which takes care of its dispatch by packing it in the wooden boxes. 2.6.3.7.1.3 ESP TRANSFORMER:
The Electrostatic Precipitator transformer is used for environmental application. It is used to filter in a suspended charge particle in the waste gases of an industry. They are of particular use in thermal power stations and cement industry. The ESP is a single-phase transformer. It has a primary and secondary. The core is laminated and is made up of CRGOS. It is a step up transformer. An AC reactor is connected in series with primary coil. The output of the transformer must be DC that is obtained by rectifying AC using a bridge rectifier (bridge rectifier is a combination of several hundred diodes). A radio frequency choke (RF choke) is connected in series with the DC output for the protection of the secondary circuit and filter circuit. The output is chosen negative because the particles are positively charged. The DC output from the secondary is given to a set of plates arrange one after the others. Impurity particles being positively charged stick to these plates, which can be jerked off. For this a network of plates has to be setup all across the plant. This is very costly process in comparison with the transformer cost. A relive vent is also provided to prevent the transformer from bursting it higher pressure develops, inside it. It is the weakest point in the transformer body. An oil temperature indicator and the secondary supply spark detector are also provided. One side of the transformer output is taken and other side has a ‘marshalling box’ which is the control box of the transformer.
In this bay power transformer are assembled. After taking different input from different bays 0-9 assembly is done.
Power transformer is used to step and step down voltages at generating and substations. There are various ratings –11KV, 22KV, manufactured, they are Generator transformer. System & Auto transformer.
A transformer in a process of assemblage is called a job. The design of the transformer is done by the design department & is unique of each job; depends on the requirement of customer. The design department provides drawing to the assembly shop, which assembles it accordingly. The steps involved in assembly are: 1. Core building 2. Core Lifting. 3. Unlacing. 4. Delacing and end-frame mounting. 5. High voltage terminal gear and low volt terminal gear mounting. 6. Vapour phasing and oil soaking 7. Final servicing and tanking. 8. Case fitting.
2.6.3.8.1Core Building: It is made of cold rolled grain oriented steel ‘CRGO’. The punched core is sent to this shop from core punching shop. Here it is assembled with the help of drawing a set of 4 laminations is called a packet. The vertical portion of the core is called a ‘leg’ the horizontal one is called as ‘yoke’. Packets of both are interlinked. It is undesirable to keep the X section of core circular to provide low reluctance part without air space. A perfect circle cannot be made so the core is stepped to achieve a near circle. The rest of the spaces left are filled with thin wooden rod. After core building the end frames are bolted. The bolts are insulated from the cores.
2.6.3.8.2 Core Lifting: 32
The core is lifted by a crane and is placed vertical. The rest of assembly is done on the core in this position. 2.6.3.8.3 Unlacing & Core Coil Assembly: The yoke of the core is removed using crane. Bottom insulation in form of 50MM thick UDEL sheets is placed PCB and press board are also used for filling the gap and to provide a good base for the coil to rest. The coil are then lowered primary, secondary, tertiary and tap in that sequences.
2.6.3.8.4 Relacing & End-frame Mounting: After lowering a coil the top insulation similar to the bottom one is provided. The removed yoke is placed end-frame bolted back into its position. The connections are then made as per drawings. All the conductors are insulated using crepe paper. Brazing copper makes the connections. For brazing silphos is used. The following tests are done during re lacing: 1. Megger Test. 2. Ratio test. 3. Meg current / High Volt test.
Testing at this stage is called pre testing. This is essential because if false are seen at a later stage; whole of the transformer will have to be dissembled.
2.6.3.8.5 H.V.T.G & L.V.T.G.: Terminals gears are accessories provided at high voltage and low voltage terminals. Main device used is tap changer. Tap changer can be on load or offload. In offload type the supply has to be tripped, then the tapings changes but in on load type the tapings can be changed while the supply is on. On load tap changer (OLTC) are used where the supply is desired to be continuous.
The upper portion of the OLTC contains mechanism by which tapping is changed. There is switch which changes tap in very small type (Micro-seconds). But there is a possibility of sparking. To get rid of it, OLTC IS filled with oil. The bottom part houses the terminals and the mechanism, which makes automatic connections. The terminals are made of thick aluminum strips.
2.6.3.8.6 Vapour Phasing & Oil Soaking: It is well known fact that water (impure) conducts electricity. Therefore, moisture presence in transformer will effect insulation; the process of moisture removal from transformer is called vapour phasing. The job is put in dummy type and place in a vacuum vessel. It is an airtight chamber with heating facilities. A solvent vessel is released is the chamber which enters all transformer parts and insulations. It absorbs water rapidly. The job is heated in vacuum. All the solvent vapours are sucked out with moisture. Metals contain no moisture but a lot of insulations is provided which contains this moisture and if not taken care of, may burst the job After moisture removal tank is filled with transformer oil and soaked for at least three hours, so that every gets wet with oil. The job remains in vessel for three days during phasing. It is then taken out of the vessel and also out of the dummy time.
2.6.3.8.7 Final Servicing & Tanking: After taking the job out of dummy time all the parts retightened any other defects are rectified and job is retimed in mild steel tank. After tanking oil is filled.
2.6.3.8.8 Case Fitting: The accessories are fixed and final touches given to job. The accessories include tank cover, fixing bushing, fixing valves etc. The terminals are marked and R and D. 34
(Rating and Diagram) plate is fixed. Bolting and not riveting because it may require maintenance and hence opening close the tank. Bushings are hollow to provide a passage for conductor; oil is filled inside the hollow spaces for better insulation. Bushing is built on a mild steel base, which is bolted to bottom chamber with a cork gasket in vacuum. The bottom chamber is mild steel tank with a steel frame attached to its base for earthling. This chamber houses the secondary winding. 2.7.1 WORK ENGINEERING & SERVICES (WE&S) This department looks after the commissioning and maintenance of all the machinery used in the factory. It also has 3 two-stage air compressors for supplying compressed air to the various bays. The department has 03 different divisions:
ELECTRICAL ENGINEERING: This division looks after all the electrical machinery and power distribution of the factory. Snags detected in the system are immediately reported to this department by the concerning department. WE&S takes prompt action to rectify it. The factory has a feeder of 11KV .The total load sanctioned for the factory is 2500MVA but the maximum demand reaches the range of 1700-2000 MVA. There are various sub-stations (SS) inside the factory, for distribution of power to different sections.
Boiler and loco plant
2.7.2 TECHNOLOGY This department analyses the changes taking place in the world and suggest changes accordingly. This is very important because the products must not get obsolete in the market otherwise they will be rejected by the customer. FUNCTIONS: Technology functions can be classified as:
Processing Sequence: The sequence of process of manufacturing is decided for timely and economic completion of the job.
Operation time estimate : It includes incentive scheme management
Allowed operation time: It includes incentive amount
Facilities identification: It includes looking for new equipment or plant or tools to increase productivity
Special process certification: Special processes are the ones requiring expertise for example identifying errors, cracks, air bubbles in welding
Special tools requirement: Special tools are allotted, if possible, when required else the design has to be reconsidered.
Productivity projects compilation: It includes the initial analysis of the problem and their appropriate solution to enhance productivity.
The principle of working is that “IF YOU DO NOT MAKE THE CHANGES IN YOUR COMPANY, THE CUSTOMER WILL CHANGE YOU”.
2.7.3 QUALITY CONTROL CENTRAL QUALITY SERVICE First we get acquainted with a few terms concerning this department. QUALITY It is the extent to which products and services satisfy the customer needs. QUALITY ASSURANCE All those plants and systematic action necessary to provide adequate confidence that a product or service will satisfy the given requirement is called quality assurance. QUALITY CONTROL The operational technique and activities that are used to fulfill requirement for quality are quality control. QUALITY INSPECTION Activities such as measuring, testing, gauging one or more characteristics of a product or service and comparing these with specified requirement to determine conformity is termed quality inspection.
3. ELECTRIC TRACTION 3.1 INTRODUCTION We the human beings are known to continuously improve our surroundings and in endeavour to do so we curiously keep reinventing with the technologies and one of such greatest inventions of man is known to be electricity which has completely made our lifestyle complacent. Be it about facing the scorching heat or resisting a chilly December night we are dependent on electricity. Our day to day life has become inaccessible without electricity. One such example is of our day to day to travelling to our workplaces for which we our dependent on metros, local emu trains, etc. This is all possible because of electricity only and electric traction has basically helped to redefine our complacent lifestyle. As an engineer what often fascinate me are what this traction is and how this all technology works and today after my
training at BHEL Jhansi I would like to share how all this stuff works with the advent of my knowledge gathered here. What is traction? This is the question that arises first in everybody’s mind and here is what the oxford dictionary has to say about it. It describes traction as an act of hauling or pulling a thing over a surface and electric traction means doing it with the aid of electricity. It means to transport men and material from one place to another as described in the book ‘Fundamentals of Electrical Drives’ by Gopal K. Dubey. Electric traction according to the same author can be broadly classified as: 1) Electric Trains 2) Electric buses, trams and trolleys 3) Battery driven and solar powered vehicles
3.2 OTHER TRACTION DEVICES MANUFACTURED AT BHEL BHEL is not only into manufacturing electric locomotives but also some various other devices required to cater the need of transportation sector. We would be discussing these devices in brief here as the next section would be dedicated to electric locomotive’s technical know-how completely. 2.1 OHE Inspection Car (Tower Wagon) This is the recording cum test car for the overhead equipment used for maintenance of OHE and for attending to break downs. It carries necessary tools for maintenance and break downs such as tackles, straining screws, clamps, ropes, ladders, adequate stock of insulators, length of contact and catenary wires and other OHE fittings. These are of two types: –
Four Wheeler (speed potential upto 75 KMPH)
Eight Wheeler (speed potential upto 110 KMPH)
Figure3.5 OHE INSPECTION CAR 3.2.2 RRV RRV stands for Rail cum Road Vehicle. It is a type of track equipment which can be run both on rail and the road.
Figure 3.6 RAIL CUM ROAD VEHICLE
3.2.3 BALLAST CLEANING MACHINE 39
This is used for cleaning of the tracks after some accident or incident has occurred on the railway tracks.
Figure 3.7 BALLAST CLEANING MACHINE
3.2.4 DYNAMIC TRACK STABILIZER This is used for track stabilization after ballast cleaning.
Figure 3.8 DYNAMIC TRACK STABILIZER 40
3.2.5 OTHER USEFUL EQUIPMENTS The various other useful equipments are shown below with their descriptions just below them a) UTILITY VEHICLE
Figure 3.9 UTILITY VEHICLE CAN BE USED FOR A HUGE NUMBER OF TASKS b) WELL WAGON Well wagon are manufactured at BHEL Jhansi for BHEL Haridwar for the transportation of turbines manufactured there. Presently, two types of well wagons have been manufactured and they are:
Figure 3.10 200T; 18 axle Well Wagon 41
Figure 3.11 280T; 24 AXLE WAGON
4. Electrical Analysis Locomotive (WAG-7)
1 Loco Section: INTRODUCTION WAG-7 is the name of a type of electric locomotive used in India. It is a very powerful locomotive in Indian Railways' fleet. Built by Chittaranjan Locomotive Works and BHEL, Jhansi to RDSO specifications. WAG7 is an up rated version of WAG-5 locomotive with high capacity transformer, rectifier, traction motor, compressor and other matching associated equipments. These are six axles loco with axle and nose suspended drive.
The loco is fitted with six Hitachi designed DC series traction motors types HS15250A, controlled by a tap changer are used in this locomotive. Indian Railway is going to achieve 700 million tones of traffic; WAG-7 is the main stay of loco. In the locomotive vehicle market WAG-7 is more economical option and one of the cheapest in the world.
1.1 Loco Commercial The main objective of this department is interaction with customer. It brings out tender and notices and also responds to them. It bags the contracts to manufacture locos. After delivery it further takes care and interrogates of faults and failures as well and takes the appropriate action to solve the problem. Its function can be broadly classified as: 1.1.1 Tendering 1. Tender: Requirement of customer comprises of the following: a) Technical specification / requirement b) Estimated cost of project / equipment c) Estimated time of completion of project d) Other information
2. Type of tenders: Broadly classified as: a) Open tender-published in news dailies, open for all b) Limited tender issued to limited parties c) Single party tender-issued to single party on propriety basis
On receipt of tender forms formal enquiries are issued to: a) Engineering department-for technical acceptance b) Production planning and control-for delivery period c) Central dispatch cell-for mode of transportation and transportation charge 4. Offer: If tender is feasible as obtained from reports of other departments offer is submitted to customer.
5. P.O /Contract Agreement: On the opening of technical bid the commercial bid of technically qualified tender is opened and order is placed on lowest value tender followed by negotiations if required. 1.1.2 Contract Execution: 1) Issue of work orders: on receipt of purchase order internal work orders are issued by commercial department for execution of work. 2) Type of work orders: 1) Technical, 2) Financial, 3) Shipping 3) Monitoring: To maintain the key dates of the contract internal meetings with the concerned departments are held on regular basis to monitor the progress. 4) Payment collection: To collect the payment from the customer. 5) Contract closing: After the dispatch and completion of all the aforesaid tasks the contract is formally closed by commercial department.
1.1.3 After sales service: 1) Within warranty period free of cost service and replacement of material if required 2) Beyond warranty period on chargeable basis 45
a variant of the standard HS15250 with higher current rating (thicker wire gauge, better insulation); Motors built by CLW and BHEL. 6 motors in parallel grouping
Traction Motors Class of Insulation for Armature and Field
Traction Motors Suspension
Axle hung and Nose-suspended
Traction Motors Weight
Traction Motors Temperature rise in Armature
90 degrees Celsius
Traction Motors Temperature Rise in Field
70 degrees Celsius
Traction Motors Temperature rise in Commutator
85 degrees Celsius
Traction Motors Coil resistance at 110 degrees Celsius of Armature
Traction Motors Coil resistance at 110 degrees Celsius of Main pole
Traction Motors Coil resistance at 110 degrees Celsius of Inter pole
Traction Motors Continuous rating
630 kW, 750 V, 900 A, 895 rpm
Traction Motors rating for 1 hour
670 kW, 750 V, 960 A, 877 rpm
Traction Motors Air gap for Main pole
Traction Motors Air gap for Inter pole
WAG-7 : 65:16 and 18:64 and WAG-7H : 65:16
CCL India, type CGTT-5400, Primary rating (5670 kVA, 252 A) Secondary rating (5400kVA, 1000V, 5400 A), Tertiary rating 270 V, 32 taps, 12200 kg, Forced Oil cooling, Class A Insulation
Two silicon rectifiers, cell type S18FN350 (from Hind Rectifier), 64 per bridge, Continuous rating 2700A / 1050V per cubicle, Max starting current 3300 A, Forced air cooling
Two Stone India (Calcutta) type AN-12, 235 kg including 4 insulators
Bogie drive arrangement
1350A/2min, 1200A/10min, 960A/hr, 900A continuous
Number of sandboxes
Lead Acid batteries
50 cells, 110 V(5 hour rating)
Arno Converter 1 phase
216 kVA, 415 V, 520 A
Arno Converter 3 phase
150 kVA, 415 V, 210 A, 1485 rpm
2 TRC-2000 type Compressors by Rigi
10.5 kg per square cm
2 Compressor Motors
30 hp, 415 V, 930 rpm
2 Exhauster Motors
7.5 kW, 415 V, 970 rpm
2 250 RE type Exhausters by Northey
4500 liters per minute
2 SF India Ltd. Traction Motor Blowers
276 cubic meters per minute
2 Traction Motor Blower Motors by Siemens
415 V, 26 kW, 50 A, 2920 rpm
2 PFT-59 type Smoothing Reactors by SF India Ltd.
4200 cubic meters per minute
2 Smoothing Reactor Motors
2.2 kW, 415 V, 2860 rpm
2 KDBR-1 type Breaking Resistor Blowers by KEC International
510 cubic meters per minute
Breaking Resistor Blower Motor
30 kW, 450 V, 76 A DC, 3300 rpm
200 X 40 X 64 mm
Brushes Wear limit
2 PHMX-40-6 type Rectifier Blowers by 3100-3200 cubic meters per hour SF India Ltd.
2 Rectifier Blower Motors
2.2 kW, 415 V, 4.8A, 2860 rpm
MLBH-60-1-H2 type Coil Cooler Blower by SF India Ltd.
22200 cubic meters per hour
Coil Cooler Blower Motor
22 kW, 415 V, 45 A, 1450 rpm
Oil Pump by Best & Co. Pvt. Ltd.
730 liters per minute
32 kW, 415 V, 2865 rpm
2 SL 30 type Smoothing Reactors
Smoothing Reactor Resistance at 110
2.3 EQUIPMENTS AT A GLANCE
Figure 3.11 BLOCK DIAGRAM OF ENGINE ROOM LAYOUT
Cab 1 COMPRESSOR
MVMT BLOWER: Cooling of traction motors.
BA-1 PANEL: Speeding control through shunt resistance.
TRIPLATE PNEUMATIC CONSOLE
DYNAMIC BRAKE RESISTANCE (DBR)
SL-30 : Removes pulses from DC signal.
SMGR (TAP CHANGER)
STATIC CONVERTER: Converts single phase current to 3 phase.
CAB 2 The above flowchart clearly gives us a handy look at the equipments used in the locomotive WAG-7. The coding of the locomotives has been already discussed in the second chapter of this report but even then I am breaking code for the present locomotive. W- BROAD GAUGE A- RUNNING IN AC MODE G- HAULING GOODS TRAIN So, this locomotive is basically made for hauling goods train or we can say its freight carrier. In this part, we had a glimpse of all the major equipments used in WAG-7 but being an Electrical & Electronics student in the coming sections my main emphasis would be on the electrical equipments being used in the locomotive WAG-7.
2.4 WAG-7 TENDER SPECIFICATION The electrical equipment should generally include: 1) Components for collection of power from the overhead system 2) Converter set comprising of main transformer, rectifier, smoothening reactors and voltage control device. 3) Auxiliary machine i.e. various rotary and static machines required for offered traction equipments. 4) Traction motor, reverser, main line contactor and field weakening devices, etc. 5) Rheostat braking equipment 6) Low voltage control equipment, protective devices/relays, etc.
7) Sanding control apparatus 8) Signaling and indicating lamp and lighting equipment Now in the sections to follow we would be seeing that what the electrical equipments that are mounted are, what is the purpose of that equipment, and its advantages.
2.5 PANTOGRAPH The pantograph is the collector used to slide along the contact wire as has been explained in section 3.6.3.1. It has a conducting strip which is pressed against the contact wire by springs. The collector strips are usually of steel with grease lubrication, or of carbon, in which case no lubrication is needed. Function of the pantograph is to maintain as constant a pressure as possible between the collector strip and contact wire and to prevent any vertical oscillation of the collector strip; as these will produce arcing due to braking of electric contact. Pantograph is used for collecting current from OHE. For this, there is an auxiliary compressor which is started firstly; this creates pressurized air so that servomotor can be started and pantograph can be raised. When the pantograph is not in use, it is maintained in lower position with the help of stiff springs. The collector strip is raised by compressed air when it is to be used.
Figure 3.13 PANTOGRAPH 54
As per the specifications, the WAG-7 locomotive shall be equipped with two pantographs having the metallised carbon strips. Normally, the trailing end pantograph will be used but a selector switch should be provided on the driver’s desk so that either or both of the pantographs can be raised. The raising up or down of the pantograph while in motion should not cause any disturbance in the OHE.
2.6 MAIN CIRCUIT BREAKER An electro pneumatically operated single bottle vacuum circuit breaker is mounted on the roof of the locomotive to connect the transformer to 25 KV AC overhead line through the pantograph and to clear any fault in traction power circuit. The breaker should be operational via a switch located in the driver’s cab. The circuit breaker should have a rupturing capacity of 400MVA and a continuous rating of 1000Amps at 25 KV. The suitable interlocks are provided for tripping the circuit breaker in case the air pressure becomes low to a value at which the raised pantograph leaves the contact wire.
2.7 LIGHTENING ARRESTOR A gapless lightening arrestor of proven design similar to those working in three phase locos is provided for protection against the line voltage transients caused by lightening or system switching.
2.8 MAIN TRANSFORMER As supply lines are to be laid all along the track, with adequate spacing, the economy dictates use of minimum number of such lines. Therefore, single phase supply is used. The current enters locomotive through the collector. This is where the use of transformer arises. The current from the collector flows through the primary of a step down transformer and returns to supply earth through locomotive wheels and one of the rails on which the locomotive travels, thus avoiding need for a second conductor. Main secondary windings of the 55
transformer feed the power modulator, which in turn powers the driving motors. The auxiliary secondary windings of the transformer feed power for other needs of the train such as lighting, fans, air conditioning etc. Now, in WAG-7 the main transformer is of oil immersed type. The oil is forced circulated through the windings by an electric pump and cooled in a radiator by a blower set. The transformer has a variable auto transformer winding incorporating various taps connected to the tap changer, the nominal voltage being 22.5 kV and maximum 27.5 kV. The transformer also has a fixed ratio transformer, the primary winding of which is connected to the auto transformer tap changer having a variable voltage from 0 to 22 kV. This transformer has two separate secondary windings. The continuous rating of rectified current is 2x2700Amps and apparent power for traction on primary and the designed power of secondary are same that is 5400kVA.
2.9 TAP CHANGER A transformer tap is a connection point along a transformer winding that allows a certain number of turns to be selected. By this means, a transformer with a variable turn ratio is produced, enabling voltage regulation of the output. The tap selection is made via a tap changer mechanism. If only one tap changer is required, tap points are usually made on the high voltage, or low current, side of the winding in order to minimize the current handling requirements of the contacts. However, a transformer may include a tap changer on each winding if there are advantages to doing so. For example, in power distribution networks, a large transformer may have an off-load tap changer on the primary winding and an on-load tap changer on the secondary winding. To minimize the number of windings and thus reduce the physical size of a transformer, a 'reversing' winding may be used, which is a portion of the main winding able to be connected in its opposite direction and thus oppose the voltage. Insulation requirements place the tap points at the low voltage end of the winding. This is near the star point in a star connected winding. In delta connected windings, the tapping is usually at the center of the winding. In an autotransformer, the taps are usually made between the series and common windings, or as a series 'buck-boost' section of the common winding.
With an on load tap-changer the transformer voltage can be varied in steps by adding or subtracting turns. For this purpose a transformer is furnished with a tapped winding and these taps are connected to terminals on the tap-changer. The tap-changer provides two basic functions, first to “select” a transformer tapping connection in an open-circuit condition, the second is to “divert” or “transfer” power to that selected tapping without interrupting the through current. In WAG-7 the tap changer is on load type oil immersed with oil circulating pump and filter. It has 32 running taps controlled by an electro pneumatic servo motor. 2.10 RECTIFIER The locomotive is provided with two sets of air-cooled silicon rectifier connected in Graetz Bridge. Each of these rectifiers are supplied by a separate secondary of the main transformer.
Fig 3.14 Rectifier
2.11 TRACTION MOTOR Traction motor refers to an electric motor providing the primary rotational torque of a machine, usually for conversion into linear motion i.e. traction. Traction motors are used in electrically powered rail vehicles such as Electric multiple units and Electric locomotives, other electric vehicles such as electric milk floats, elevators and conveyors as well as vehicles with electrical transmission systems such as diesel-electric and electric hybrid vehicles. Additionally the electric motors in other products such as the main motor in washing machines are described as traction motors.
Fig 3.15 traction motor Before the mid-20th century, a single large motor was often used to drive multiple driving wheels through connecting rods that were very similar to those used on steam locomotives. It is now standard practice to provide one traction motor driving each axle through a gear drive. Usually, the traction motor is simply suspended between the truck (bogie) frame and the driven axle; this is referred to as a "nose-suspended traction motor". The problem with such an arrangement is that a portion of the motor's weight is unsprung, increasing forces on the track.
In WAG-7 the traction motor used is of series DC pulsating current type. The armature is vacuum pressure impregnated solvent less resin. The motor fulfils the following parameters broadly: Mounting: Axle hung nose suspended Rating: One hour: 750V, 960A, 870RPM, 670 kW Continuous: 750V, 900A, 895RPM, 630kW Weak field: 40% Maximum permissible Ripple: 28% at continuous current of 900A Starting current: 1350A for 2 minutes Short time rating: 1200A for 10 minutes
2.11 FUNCTIONAL DESCRIPTION OF MAIN CIRCUIT OF WAG-7 1. GENERAL OUTLINE Fig.1 shows a simplified diagram of main circuit.The current is taken from the 25KV 50HZ overhead line by pentograph and passes through the main circuit breaker to the primary winding of the main transformer and through the grounding transformer (GT) of the car body. The purpose of the GT is to ensure that the current going through the car body finally finds its way thrpugh the wheels and is then earthed via the the rails.
Fig 3.16 simplified diagram of main circuit In addition to the four traction windings, secondary windings are connected to the auxiliary power system.
2. TRACTION MOTOR MODULES Fig 3.17 shows the armature circuit for one motor module.In the convertors,which are built up from thyristors and diodes, the 50Hz supply voltage is rectified and fed to the traction motors.To smooth the current from the convertors smoothing reactor is connected in series with each motor.
Fig 3.17 one motor module Connected parallel to each traction winding,the power factor control has the form of three tuned LC links.Between the transformer and the convertors,automatically operated module disconnectors (MD) are connected which also disconnect the field circuit of the module.
Fig 3.18 Field circuit
3. CONVERTORS The convertors consist of thyrstors and diode to allow a path for the free wheeling current when the thyristors are not fired. During acceleration,one bridge only is being fired until shortly before it is advanced.Then the two bridges are both fired until the first one is fully advanced,after which the second is further advanced, after which the second ic fully advanced,until it too is fully fired.This procedure is called ‘Overtapping control’. Phase angle control of the thyristor will introduce harmonics and because of this, both power factor and psophometric current will vary considerably at different speeds.In order to minimize the influence on the supply network, Power Factor Control (PFC) is used.
Fig 3.19 PFC system
4. FIELD CIRCUIT The field circuit feeds the motor field windings, each of which is individually controlled. During acceleration from standstill, the field current is kept approximately constant until maximum motor voltage (or maximum available voltage) is reached. In order to further increase the speed, field weakening must take place.
5. SAFETY MONITORING AND FAULT DETECTION
For safety and monitoring purposes,current transformers and breakers are used. To curve over voltage, a lightning arrestor (LA) is used, limiting the maximum voltage over the main transformer.The current in all windings of the main transformer and all motor fields is monitored continuously through the use of current transformer (CT).
When an over current occurs on any of the main transformers, the main circuit breaker (MCB) will open immediately. The potential transformer (PT) is used for monitoring the supply votage.When supply voltage is too low or too high, the MCB is opend.To enable the driver immediately discover the fault in locomotive and if possible,reset from the cab, a computerized fault indicating system (FIS) has been incorporated. This system consists of a microprocessor which supervises all running conditions. Together with a display panel in each driver’s cab this gives the driver all necessary information during fault conditions and also provides possibility to reset most of the faults from the driver cab through a push button.
Fig 3.20 Safety and monitoring system
2.12 RHEOSTATIC BRAKING 63
Dynamic braking is the use of the electric traction motors of a railroad vehicle as generators when slowing the vehicle. It is termed rheostatic if the generated electrical power is dissipated as heat in brake grid resistors and regenerative if the power is returned to the supply line. Dynamic braking lowers the wear of friction braking components and additionally regeneration can also lower energy consumption. During braking the motor fields are connected across either the main traction generator (Diesel-electric loco) or the supply (Electric locomotive) and the motor armatures are connected across either the brake grids or supply line. The rolling locomotive wheels turn the motor armatures, and if the motor fields are now excited, the motors will act as generators. For a given direction of travel, current flow through the motor armatures during braking will be opposite to that during motoring. Therefore, the motor exerts torque in a direction that is opposite from the rolling direction. Braking effort is proportional to the product of the magnetic strength of the field windings, times that of the armature windings. The locomotive WAG-7 is equipped with rheostatic braking arrangement capable of braking effort of around 20T over a speed range of 25 to 50 km/h. In the event of failure of the electric brake brakes on the train the air brake on the locomotive will be applied automatically. Braking effort regulation are obtained by adjustments of the traction motor excitation. The field of all the motors are connected in series and fed by one of the two silicon rectifier bridge connected by means of an intermediate transformer to one of the two secondary windings of the transformer. The control of the excitation is provided by the tap changer. The dynamic braking resistance is forced cool by AC motor blower set (AC MVRF). In case of emergency brake application by the driver, the electric brake, if applied will be automatically cut off.
2.13 BATTERY Batteries of adequate capacity are provided on the locomotive to feed the equipment for three hours starting with a half charged battery when the locomotives are coupled in multiple. The battery can be of lead acid type or latest with PPCP containers.
2.14 CONTROL EQUIPMENT & SAFETY DEVICES The LED flashers light are provided in the locomotive. The microprocessor based control and fault diagnostic systems are there which can even indicate the availability of OHE power supply through capacitive coupling. The safety devices include a new feature in the locomotives manufacturing. The Vigilance Control Device (VCD) has been installed on WAG-7. The driver has to acknowledge to periodic vigilance check by pressing a push button. In case the driver is not vigilant with the first step then the device will flash an indication. If even now, the driver does not respond then an audio-visual warning will be played and in case of no response automatically the emergency brakes will be applied and the whole loco has to be started all again.
2.15 POWERING OF SINGLE PHASE LOAD This part is not associated with the manufacturing but is an important part of traction system and I believe this report would be incomplete without discussing this part. The locomotive power ratings can be as high as 6000 HP. The WAG-7 has a power rating of 5000 HP and powering such a large single phase load can lead to large unbalance in the supply system which is always three phase. Due to this the track supply is divided into sections which are electrically isolated from each other, and substations supplying these sections are connected to different phases of the three phase supply. Though the unbalance is reduced, its magnitude still remains large. If the three phase supply system capacity is much larger than the power drawn by the locomotive, then this unbalance will not significantly affect the three phase supply system. Therefore, it is essential that the main source of traction supply should be sufficiently large.
25 KV AC Single phase
Figure4.4 SCHEMATIC DIAGRAM OF TRACTION SUBSTATION
2.16 PNEUMATIC BRAKING SYSTEM In the air brake's simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical linkage to brake shoes that can rub on the train wheels, using the resulting friction to slow the train. The mechanical linkage can become quite elaborate, as it evenly distributes force from one pressurized air cylinder to 8 or 12 wheels. The pressurized air comes from an air compressor in the locomotive and is sent from car to car by a train line made up of pipes beneath each car and hoses between cars. The principal problem with the straight air braking system is that any separation between hoses and pipes causes loss of air pressure and hence the loss of the force applying the brakes. PNEUMATIC FUNCTIONS IN WAG-7
Pressurized or compressed air is used for following proposes in WAG-7: 1) IN CONTACTORS- BA panels are there, two in number that are consisting of various contactors and pneumatic valves. Because of very high voltage of 25KV, there is possibility of very heavy sparking while switching on various switches, therefore these contactors are used in which pressurized air is passed through magnetic and pneumatic valves which reduces chances of sparking and makes contacts with switches.
2) IN WIPING, HORN AND SANDING- This is also a major use of air in locomotives. There are separate reservoirs for every operation. 3) AIR BRAKING: The vast majority of the world’s trains are equipped with braking systems which use compressed air as the force used to push blocks on the wheels or pads on to discs. These systems are known as “air brakes” or “pneumatic brakes”. Changing the level of air pressure in the pipe causes a change in the state of the brake on each vehicle. It can apply the brakes, release it or hold it “on” after a partial application.
INDEPENDENT BRAKING THROUGH SA-9 BRAKE VALVE
SA9 brake system is used only when engine is running alone. The compressor supply compressed air to fill up reservoirs MR1, MR2, MR3 & MR4. MR2 & MR3 and MR3 & MR4 are connected through check valves which permit flow of air in one direction only. MR3 is used for other connections like sand, wiping and electric controls. Thus for any leakage in MR3, the pressure in reservoir MR4 will not drop. After MR4 there is an isolating cock to provide facility for cutting off of air supply. The system is placed in both the cabs and can be operated from any cab. However while operating the brakes from any cab; the control from the other cab must be closed. To facilitate this two isolating cocks for provided to each cab. The supply of MR4 reaches to port 1 of C2W relay valve from where it can be transmitted to brake cylinders. On released situation port 30 is connected with port 20. This allows pressure to flow till port 2 of MU2B valve. The pressure reaches to port 20 of MU2B valve. Thus there is pressure build up at port 2 of C2W relay valve. The pressure at port 2 proportionally closes port 1 of C2W and port 3 is connected to exhaust. So in released position brake cylinders are connected to exhaust at atmospheric pressure. Hence there is no braking. When the handle in one of the cab is moved to applied position, post 20 gets connected to exhaust and there is no pressure build up at 2 of MU2B valve. The pressure at port 20 of MU2B falls which results in fall in pressure at port 2 of C2W relay valve. The fall in pressure proportionally allows port 1 of C2W relay valve to connect with port 3. Thus the pressure from MR4 reaches to brake cylinders via port 1 and port 3 of C2W relay valve. Hence brakes are applied.
THROUGH A9 AUTO BRAKE VALVE
A9 brakes system is used when the engine is connected with bogies. Like as SA9, this system has compressor, 4 main reservoirs and different valves. The system is same in both the cabs. When the handle of the brake u=is set to release position, port 30 is connected to port 5 and a pressure of around s kg/cm² is build up in BP. The pressure flows through port 3 and port 13 of MU2B and reaches to port 2 of C2W relay valve. The pressure at port 2 proportionally 69
connects port 1 to port 3. Thus there is pressure build at BP and MR disconnects to BC. So pressure at brake cylinders falls and there is no braking. In applied position port 30 disconnects to port 5 and port 5 connects to exhaust in proportion of handle moved. The pressure falls at port 3 and 13 of MU2B which reaches to port 2 of C2W relay valve. The fall in pressure proportionally disconnects port 1 and port 3 of C2W valve. The pressure at BP thus falls which proportionally connects MR to BC. Pressure at BC through valves of F1 selector valve reaches to brake cylinders and hence brakes are applied. The pressure from C3W distributor valve reaches to F1 selector valve via N1 reducing valve which reduces pressure to 1.8 kg/cm². When the brake valve handle is moved in the minimum reduction position, reduction of pressure in the brake pipe by 0.2 to 0.5 kg/cm² is achieved and proportional application of brakes on loco and train takes place. In full service of the automatic brake valve handle, the BP pressure is reduced to 3.5 kg/cm² and in over reduction to 2.5-2.6 kg/cm² is achieved. When the driver feels that it is not necessary to apply brake on the loco, during automatic application of the brake release pedal switch is pressed to release the loco brakes. The d1 pilot air valve is energized to cut off the automatic air brakes on the loco while train brakes remains applied on the trailing stoc at the quickest possible time.
EMERGENCY BRAKE There is an emergency brake valve which is provided on assistant driver’s side in cab, which is being applied during emergency conditions. During its application the complete BP pressure is directly exhausted through its exhaust port and air brake is performed through C3W distributor valve as well as A9 brake system.
DYNAMIC BRAKING IN WAG-7
Dynamic braking is the use of the electric traction motors of a railroad vehicle as generators when slowing the locomotive. It is termed rheostatic if the generated electrical power is dissipated as heat in brake grid resistors, and regenerative if the power is returned to the supply line. Dynamic braking lowers the wear of friction-based braking components, and additionally regeneration can also lower energy consumption. PRINCIPLE OF OPERATION During braking, the motor fields are connected across either the main traction generator (diesel-electric loco) or the supply (electric locomotive) and the motor armatures are connected across either the brake grids or supply line. The rolling locomotive wheels turn the motor armatures, and if the motor fields are now excited, the motors will act as generators. During dynamic braking the traction motors which are now acting as generators are connected to the braking grids (Large resistors) which put a large load on the electrical circuit. When a generator circuit is loaded down with resistance it causes the generators to slow their rotation. By varying the amount of excitation in the traction motor fields and the amount of resistance imposed on the circuit by the resistor grids, the traction motors can be slowed down to a virtual stop (approximately 3-5 MPH). For permanent magnet motors, dynamic braking is easily achieved by shorting the motor terminals, thus bringing the motor to a fast abrupt stop. This method, however, dissipates all the energy as heat in the motor itself, and so cannot be used in anything other than low-power intermittent applications due to cooling limitations. It is not suitable for traction applications. RHEOSTATIC BRAKING The electrical energy produced by the motors is dissipated as heat by a bank of onboard resistors. Large cooling fans are necessary to protect the resistors from damage. Modern systems have thermal monitoring, so if the temperature of the bank becomes excessive, it will be switched off, and the braking will revert to friction only. REGENRATIVE BRAKING In electrified systems the similar process of regenerative braking is employed whereby the current produced during braking is fed back into the power supply system for use by other traction units, instead of being wasted as heat. It is normal practice to incorporate both regenerative and rheostatic braking in electrified systems. If the power supply system is not "receptive", i.e. incapable of absorbing the current, the system will default to rheostatic mode in order to provide the braking effect. Yard locomotives with onboard energy storage systems which allow the recovery of some of this energy which would otherwise be wasted as heat are now available. The Green Goat model, for example, is being used by Canadian Pacific Railway, BNSF Railway, Kansas City Southern Railway and Union Pacific Railroad.
On modern passenger locomotives equipped with AC inverters pulling trains with sufficient Head End Power loads braking energy can be used to power the train's on board systems as a form of regenerative braking if the electrification system is not receptive or even if the track is not electrified to begin with. The HEP load on modern passenger trains is so great that some new electric locomotives such as the ALP-46 were designed without the traditional resistance grids.
BLENDED BRAKING Dynamic braking alone is insufficient to stop a locomotive, as its braking effect rapidly diminishes below about 10 to 12 miles per hour (16 to 19 km/h). Therefore it is always used in conjunction with the regular air brake. This combined system is called blended braking. Liion batteries have also been used to store energy for use in bringing trains to a complete halt. Although blended braking combines both dynamic and air braking, the resulting braking force is designed to be the same as what the air brakes on their own provide. This is achieved by maximizing the dynamic brake portion, and automatically regulating the air brake portion, as the main purpose of dynamic braking is to reduce the amount of air braking required. This conserves air, and minimizes the risks of over-heated wheels. One locomotive manufacturer, Electro-Motive Diesel (EMD), estimates that dynamic braking provides between 50% to 70% of the braking force during blended braking.
This report clearly replicates the tremendous growth of a company which continuously renovated its technology to contribute not only in the infrastructure building in India but also of the world. It is an asset for our country to have such a public sector industry which has fulfilled the dream of our first Prime Minister Sh.
Jawahar Lal Nehru by operating in 65 countries and making it go global. The vision and mission of this company are successful can be adjudged with the faith of the stake holders in this company. BHEL Jhansi although a smaller unit in comparison to other units of BHEL, is a very productive one with the manufacturing of the electric locomotives, power transformers, etc. The work load here can be accessed from the fact that the order of the locomotives has forced the company to shift its Bus duct section to the other unit of BHEL. Presently company is about to finish its project on BCM machine, it clearly shows that company has good working
hands on the coming technology and has rapid pace of working. In future also the company is having orders of metro coaches and this clearly shows why this company is still recession proof. And the designing department has started to work on the technology of WAG-9 so that it can take fresh orders of WAG-9 from Indian Railways.
Books/Manuals Gopal K. Dubey, Fundamentals of Electrical Drives, Second Edition, Fifteenth Reprint, Narosa Publishing House Pvt. Ltd.,2008 Ashfaq Hussain, Electric Machines, Second Edition, Dhanpat Rai & Co.,2008 Y.P.Singh, Presentation on Standards and Practices Overhead Electric Equipments. Presentation on Locomotive Manufacturing by BHEL. Presentation on Locomotive Planning by BHEL. WAG-7 Tender Specification by RDSO Lucknow. Presentation on BCM by BHEL. Presentation on Basic Welding Process by BHEL. General drawing’s by LME Dept. Presentation on WE & S by BHEL.
