Evolution of Electrical Rolling Stock
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Questions and Answers

What was a significant factor that allowed for the large-scale application of single phase 50Hz 25kV for mainline electrification?

  • Import of Japanese locomotives
  • Advancements in AC traction technology
  • Use of high-speed DC motors
  • Development of mercury arc rectifiers (correct)

    • Which type of rectifier offered an additional advantage of reversibility?

  • Mercury arc rectifiers
  • Excitrons (correct)
  • Thyristor converters
  • Silicon rectifiers

    • What is primarily used for voltage control in locomotives with mercury arc and silicon rectifiers?

  • Digital controllers
  • Electro-pneumatically operated tap changers (correct)
  • Phase angle switches
  • Manual switches

    • What was a notable feature of the silicon diode devices in modern AC locomotives?

    <p>They are simple to maintain and extremely reliable</p> Signup and view all the answers

    Which locomotives were mentioned as employing silicon rectifiers for conversion?

    <p>WCAM-1 and YAM-1</p> Signup and view all the answers

    What advantage do thyristor converters have over silicon rectifiers in certain WAG-1 and WAM-2 locomotives?

    <p>Phase angle control</p> Signup and view all the answers

    In comparison to DC locomotives, what significant benefit do AC locomotives provide?

    <p>Increased reliability in performance</p> Signup and view all the answers

    What component is responsible for taking supply current from the overhead conductor?

    <p>Pantograph</p> Signup and view all the answers

    Which of the following components is connected to the high-voltage end of the transformer primary winding?

    <p>Lightning arrestor</p> Signup and view all the answers

    What is the purpose of the primary-overload relay?

    <p>To protect the main transformer</p> Signup and view all the answers

    Which component is primarily responsible for providing surge suppression in the rectifier case?

    <p>Surge-suppression fuses</p> Signup and view all the answers

    Where is the earth cable connected in relation to the traction motors?

    <p>To the axle earth-brushes</p> Signup and view all the answers

    What is the primary purpose of the grounding transformer (GT) in the main circuit?

    <p>To ensure the current returns to the earth via the wheels and rails.</p> Signup and view all the answers

    How are the traction motor modules controlled in the main circuit?

    <p>Individually, depending on adhesion conditions.</p> Signup and view all the answers

    What does the term 'overlapping control' refer to in the context of the convertors?

    <p>Gradual firing of the thyristors in sequence.</p> Signup and view all the answers

    What do the LC-links connected parallel to each traction winding achieve?

    <p>They control the power factor and smoothen current flow.</p> Signup and view all the answers

    What type of motors are used in the traction system as specified in the document?

    <p>Separately excited dc motors with bogie suspension.</p> Signup and view all the answers

    Which component rectifies the 50 Hz supply voltage before it is fed to the traction motors?

    <p>Convertors consisting of thyristors and diodes.</p> Signup and view all the answers

    What role does the power factor control equipment (PFC) play in the system?

    <p>It minimizes harmonics introduced by the phase angle control.</p> Signup and view all the answers

    What happens to the power delivered to the motors during acceleration according to the document?

    <p>Only one bridge is fired until it is fully advanced.</p> Signup and view all the answers

    What does the smoothing reactor do in each motor circuit?

    <p>It smooths the current from the convertors.</p> Signup and view all the answers

    What happens if an over current occurs on any of the monitoring transformers?

    <p>The main circuit breaker will open immediately.</p> Signup and view all the answers

    What is the purpose of the potential transformer (PT) in the system?

    <p>To monitor the supply voltage.</p> Signup and view all the answers

    What method is used to enable the driver to discover faults and possibly reset them from the cab?

    <p>Computerized fault indicating system (FIS).</p> Signup and view all the answers

    How is the current from the overhead line processed in the main circuit?

    <p>It passes through the main circuit breaker to the primary winding of the main transformer.</p> Signup and view all the answers

    What type of control is employed during the acceleration phase of the convertors?

    <p>Overlapping control.</p> Signup and view all the answers

    What is the function of the smoothing reactors in the circuit?

    <p>They provide a steady current flow to the traction motors.</p> Signup and view all the answers

    What effect does phase angle control of the thyristors have on power quality?

    <p>It introduces harmonics and varies power factor and psophometric current.</p> Signup and view all the answers

    What is the role of the power factor control equipment (PFC)?

    <p>To minimize the influence of harmonics on the supply network.</p> Signup and view all the answers

    How is the traction motor armature circuit organized?

    <p>Into two groups of three traction motors each.</p> Signup and view all the answers

    What is the electrical characteristic of the convertors regarding free wheeling current?

    <p>They provide a path for free wheeling current when thyristors are not fired.</p> Signup and view all the answers

    What is the approximate ratio of separate field strength to series field strength in traction motors?

    <p>60:40</p> Signup and view all the answers

    How are the traction motors suspended in WAG-6B and WAG-6C models?

    <p>Fully suspended in WAG-6B, nose-suspended in WAG-6C</p> Signup and view all the answers

    During acceleration, how is the field current managed until maximum motor voltage reference is achieved?

    <p>It is increased proportionally with armature current.</p> Signup and view all the answers

    When does the first power factor correction (PFC) unit switch on?

    <p>When the primary current reaches 100A.</p> Signup and view all the answers

    What device is used to limit the maximum voltage over the main transformer to curb over voltage?

    <p>Lightning arrestor</p> Signup and view all the answers

    What happens when an over current occurs on any of the monitoring transformers?

    <p>The main circuit breaker (MCB) opens immediately.</p> Signup and view all the answers

    What is the primary role of the potential transformer (PT) in the safety monitoring system?

    <p>To monitor supply voltage levels.</p> Signup and view all the answers

    What is the purpose of the computerized fault indicating system (FIS) in the traction motor setup?

    <p>To supervise running conditions and indicate faults.</p> Signup and view all the answers

    What defines the braking characteristics during rheostatic breaking?

    <p>Field current is reduced based on required braking characteristics.</p> Signup and view all the answers

    What is the role of current transformers (CT) in the safety monitoring system?

    <p>To continuously monitor the current in all windings.</p> Signup and view all the answers

    Which component is primarily responsible for protecting the main transformer from overload conditions?

    <p>Primary-overload relay</p> Signup and view all the answers

    What is the function of the lightning arrestor in the electric traction context?

    <p>To divert excess voltage surges away from electrical components</p> Signup and view all the answers

    Which component connects to the insulated earth cable to facilitate the return circuit to the running rails?

    <p>Traction motors</p> Signup and view all the answers

    Which of the following components is NOT associated with the rectifier case?

    <p>Motor overload relays</p> Signup and view all the answers

    What role does the high-voltage end of the transformer serve regarding other components?

    <p>Connects to the lightning arrestor and provides surge protection</p> Signup and view all the answers

    What technological advancement in rectifiers significantly improved the performance of AC locomotives over DC counterparts?

    <p>High Power Silicon Diode Devices</p> Signup and view all the answers

    What is the primary factor that allowed for better reliability in newer rectifiers used in locomotives?

    <p>Silicon rectifiers</p> Signup and view all the answers

    In which locomotives was the phase angle controlled thyristor converter notably implemented as a replacement?

    <p>WAG-1 and WAM-2</p> Signup and view all the answers

    Which type of control mechanism is used for voltage adjustment in locomotives utilizing mercury arc and silicon rectifiers?

    <p>Electro-pneumatically operated tap changers</p> Signup and view all the answers

    Which class of locomotives uses silicon rectifiers and operates in a single isolated section?

    <p>YAM-1</p> Signup and view all the answers

    What was a disadvantage of AC traction motors compared to their DC counterparts before advancements in technology?

    <p>Inferior performance</p> Signup and view all the answers

    What additional functionality do excitrons provide over the earlier mercury arc rectifiers?

    <p>Ability to convert AC back to DC</p> Signup and view all the answers

    Which drive arrangement is utilized in WAM2 and WAM3 locomotives?

    <p>WN coupled gear drive</p> Signup and view all the answers

    What is the starting tractive effort of monomotor bogie locomotives mentioned in the content?

    <p>32 tonnes</p> Signup and view all the answers

    Which design of bogie is used in the indigenous WAG5 locomotives?

    <p>Trimount bogies of ALCO design</p> Signup and view all the answers

    What unique feature does the WAG-6A locomotive utilize for its drive system?

    <p>ASEA hollow shaft drive system</p> Signup and view all the answers

    What type of bogie modification is included in the WAP-1 locomotives?

    <p>Flexicoil bogie</p> Signup and view all the answers

    How many axles do the WAG-6 locomotives have to achieve high tractive efforts?

    <p>6 axles</p> Signup and view all the answers

    Which class of locomotives was primarily manufactured at Chittranjan Locomotive Works until the early seventies?

    <p>WAG 1 and WAG 4</p> Signup and view all the answers

    What is the design characteristic of the bogies used in WAG-6B locomotives?

    <p>Bogie with high adhesion</p> Signup and view all the answers

    What limitation is noted concerning the starting tractive effort of locomotives in the context provided?

    <p>Limited by bridge capacity to 37.5t</p> Signup and view all the answers

    What action does the main circuit breaker (MCB) take when an over current is detected in the monitoring transformers?

    <p>It opens immediately.</p> Signup and view all the answers

    How does the computerized fault indicating system (FIS) assist the driver during operation?

    <p>It offers real-time monitoring and fault reset capability from the cab.</p> Signup and view all the answers

    During the acceleration phase of the locomotives, what is unique about the firing sequence of the convertors?

    <p>Only one bridge is fired initially, followed by the other just before full acceleration.</p> Signup and view all the answers

    What are smoothing reactors used for in the circuit?

    <p>To provide a steady current to the traction motors.</p> Signup and view all the answers

    What is the main benefit of using power factor control equipment (PFC) in the system?

    <p>It enhances the overall efficiency by reducing harmonics.</p> Signup and view all the answers

    What does overlapping control of thyristors accomplish during locomotive acceleration?

    <p>It allows for efficient management of electrical load.</p> Signup and view all the answers

    Which component is primarily responsible for monitoring the supply voltage in the system?

    <p>Potential transformer (PT)</p> Signup and view all the answers

    How is the traction motor armature circuit organized in the WAG-6B/WAG-6C models?

    <p>Divided into two groups of three traction motors each.</p> Signup and view all the answers

    What happens if the potential transformer (PT) detects an abnormal supply voltage?

    <p>It triggers an immediate opening of the MCB.</p> Signup and view all the answers

    During which conditions might the driver use the push button in the driver's cab?

    <p>To reset most faults indicated by the FIS.</p> Signup and view all the answers

    What is the maximum haulage capacity for passenger services at 60 km/h on a 1/200 grade?

    <p>1215 tonnes</p> Signup and view all the answers

    Which grade requires the least amount of haulage capacity for a starting service according to the provided data?

    <p>1/50</p> Signup and view all the answers

    At what speed does the maximum haulage capacity for coaching stock drop below 500 tonnes?

    <p>110 km/h</p> Signup and view all the answers

    What haulage capacity is listed for freight service at a grade of 1/150 for speeds of 90 km/h?

    <p>830 tonnes</p> Signup and view all the answers

    For a service grade of 1/100, at what speed does the haulage capacity for ICF reach 600 tonnes?

    <p>90 km/h</p> Signup and view all the answers

    Which of the following is NOT an indicated maximum haulage capacity for passenger services at 40 km/h?

    <p>1010 tonnes</p> Signup and view all the answers

    What is the maximum haulage capacity for service stock at a grade of 1/200 and speed of 120 km/h?

    <p>715 tonnes</p> Signup and view all the answers

    At 110 km/h, what is the maximum haulage capacity for a service on a grade of 1/150?

    <p>710 tonnes</p> Signup and view all the answers

    Which speed corresponds to the maximum haulage capacity of 4340 tonnes at level grade?

    <p>60 km/h</p> Signup and view all the answers

    For a coaching stock at 1/50 grade, what is the maximum haulage capacity at 80 km/h?

    <p>490 tonnes</p> Signup and view all the answers

    Study Notes

    Evolution of Electrical Rolling Stock

    • Electrical locomotives use mercury arc rectifiers (initially water-cooled) to convert AC to DC, then later, air-cooled rectifiers (excitrons) for more reliable solutions.
    • Excitrons, a later solution, offered the advantage of reversibility, converting DC to AC for regeneration purposes.
    • With the development of high-power silicon diode devices, a significant advancement was made in the design of AC locomotives. Silicon diode technology is simpler to maintain and highly reliable.
    • The utilization of silicon rectifiers and a tap-changer controlled system for voltage regulation is now widely employed in Indian Railways' locomotive fleet.
    • Some locomotives use phase-angle-controlled thyristor converters for voltage control, replacing the older silicon rectifier setup.
    • Electrical multiple units (EMUs) and motor-generator (MG) locomotives also use silicon rectifiers for conversion in different sections.

    Sources of Electric Locomotives

    • Indian Railways imported WAP-1 and WAP-3 locomotives (using Co-Co flexi-coil bogies for higher speeds).
    • WAG-1 and WAG-2 (higher adhesion mono motor bogies) locomotives were also imported.
    • Some locomotives have been manufactured at Chittaranjan Locomotive Works (CLW).
    • CLW has manufactured various series of locomotives including WAM-4 and WAG-5.

    Mechanical Concepts

    • Different axle locomotive designs (WAM1, WAM2, WAM3, WAG1, WAG3, WAG4, WAG2) have utilized varied drive mechanisms (e.g., cordon shaft drive, coupled gear drive, monomotor bogies with flexible rubber couplings) for traction.
    • The performance of some locomotive designs (e.g., WAG1, WAG2, WAG3) was deemed inadequate for later requirements.

    Diagrams and Layouts

    • Detailed diagrams provide layouts of equipment like master controllers, driver seats, and specific components like transformers, tap changers, and rectifiers for various loco types (WAM-1, WAM-2, WAP-1, WAG-5, WAG-6).
    • Data on components like transformers, rectifiers, and other vital equipment for different locomotive classifications (e.g., WAG 1, WAG 4, WAM 3), also provided in the appendix.
    • Diagrams of layouts within train units (e.g., the WAU-4 EMU) are included.
    • Diagrams are included for the power circuit in WAG-6A, including module disconnectors (MDs) between the convertors and the transformer.

    Electrical Equipment

    • Detailed specifications such as type, gauge, dimensions, axle load, weight, bogie arrangement, traction motor, and brake systems are given for various types of locomotives.
    • Data on various components and configurations for locomotives from different manufacturers (e.g., Hitachi, ASEA) is included.
    • Components like braking systems, transformers, rectifiers, and switch arrangements are explained.

    Power Factor Correction (PFC)

    • The PFC system is used in AC locomotive circuits to improve the power factor and reduce harmonics.
    • The system uses tuned LC-links to compensate for capacitive variations during operation.
    • An efficient PFC system is vital for the smooth running and performance of AC locomotives.

    Safety and Fault Detection

    • Safety monitoring is managed using current transformers, breakers, and the main circuit breaker (MCB).
    • An indicating system (FIS) monitors operating conditions with displays in the drivers cabin.
    • Fault detection and troubleshooting capabilities of the systems used in AC locomotives are described.

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    Description

    Explore the advancements in electrical locomotives and their conversion technologies. This quiz covers the transition from mercury arc rectifiers to modern silicon diode devices, highlighting their significance in enhancing reliability and maintainability. Test your knowledge of electric locomotive systems used in railways.

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