Power Supply for Traction: Indian Railways
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Questions and Answers

What is the priority for the provision of power factor improvement capacitors at traction substations?

  • Substations with the highest power consumption
  • Substations located near urban areas
  • Substations feeding large marshalling yards and where penalties for low power factor apply (correct)
  • Substations with the most recent technology

    • How is the average monthly power factor calculated?

  • By multiplying KWh and KVAh over a month
  • By subtracting KVAh from KWh and then averaging over a month
  • As the ratio of KWh to KVAh over a month (correct)
  • By dividing KVAh by total energy consumption over a month

    • What should be considered when planning the selection of KVAr rating for capacitors?

  • The distance of the substation from the central grid
  • The age of the existing transformers
  • The power factor trend observed over the past years
  • The guidelines issued by RDSO (correct)

    • What is required when total shut-down of EHV and 25 Kv supply becomes unavoidable?

    <p>Advance notice to Sr.DEE/DEE(TRD) with reasons for the shut-down</p> Signup and view all the answers

    What key aspect should be included in the operating instructions for grid and traction substations?

    <p>Procedure for carrying out switching operations</p> Signup and view all the answers

    What charge is applied when the power factor falls below a specified value?

    <p>Penalty for low power factor</p> Signup and view all the answers

    How is the Excess Energy calculated according to the given formula?

    <p>Excess Energy = TU (1 - CD/MD)</p> Signup and view all the answers

    What does the Minimum Guarantee typically represent in an agreement with the SEB?

    <p>A percentage of the capital cost invested by SEB</p> Signup and view all the answers

    What factor does the Billing Demand typically relate to?

    <p>Contract demand or actual maximum demand</p> Signup and view all the answers

    In case of excess over Contract Demand, what implication does it have for the units of energy charged?

    <p>They are charged at a higher tariff excluding FAC.</p> Signup and view all the answers

    What is the role of the Fuel Adjustment Charge (FAC)?

    <p>To account for variations in fuel costs and calorific values.</p> Signup and view all the answers

    What happens if the actual Maximum Demand exceeds the Contract Demand for a short period?

    <p>Proportionate units for the entire month are charged at a penal rate.</p> Signup and view all the answers

    What is the maximum allowable individual harmonic voltage distortion (Vn) at the point of supply?

    <p>3%</p> Signup and view all the answers

    What should be ensured regarding the Maximum Demand charged?

    <p>The addition of both trivector meters should not be taken as MD.</p> Signup and view all the answers

    What is the required action if the accuracy of the single set of meters is in doubt?

    <p>The Railway is entitled to ask for testing and certification.</p> Signup and view all the answers

    How should billing figures be determined when two sets of meters are provided?

    <p>Based on the average readings of both sets of meters.</p> Signup and view all the answers

    What is the minimum load factor often specified in agreements with SEBs?

    <p>30%</p> Signup and view all the answers

    Who should participate in taking the monthly meter readings?

    <p>Supply Authority representatives and Railway representatives.</p> Signup and view all the answers

    What additional information should be obtained during visits to grid sub-stations?

    <p>Daily maximum demand, power factor, and load factor.</p> Signup and view all the answers

    How often should the tariff charged for traction be reviewed?

    <p>Periodic reviews are necessary.</p> Signup and view all the answers

    What should be done with the meter card and printomaxigraph chart readings after taking meter readings?

    <p>They must be initialed by both parties' representatives.</p> Signup and view all the answers

    What is the role of harmonic analysis in voltage supply?

    <p>To ensure harmonic voltage distortion does not exceed specified limits.</p> Signup and view all the answers

    What is the formula used to calculate harmonic voltage distortion (Vn)?

    <p>$ rac{(V2)^2 + (V3)^2 + ... + (V13)^2}{V} \times 100$</p> Signup and view all the answers

    What is essential for the power supply for electric traction before it is actually utilized?

    <p>An agreement with the concerned Supply Authority</p> Signup and view all the answers

    What is the effect of emergency working on the maximum demand at sub-stations?

    <p>It may temporarily increase the maximum demand</p> Signup and view all the answers

    What methodological change has been agreed upon by the Central Electricity Authority regarding traction power charging?

    <p>Charging based on simultaneous maximum demand of connected sub-stations</p> Signup and view all the answers

    What factor should be carefully considered to minimize energy costs in Electric Traction?

    <p>The tariff structures of various state Electricity Boards</p> Signup and view all the answers

    How should contract demand for each sub-station be stipulated?

    <p>According to expected actual maximum demand to avoid extra charges</p> Signup and view all the answers

    What should be the notice period for altering Contract Demand according to the ideal agreement?

    <p>4 to 6 weeks</p> Signup and view all the answers

    Which statement about the tariff for electric traction is accurate?

    <p>Some states employ a complex tariff structure based on various parameters.</p> Signup and view all the answers

    What is one of the primary purposes of scrutinizing the Supply Authorities' bills?

    <p>To identify energy consumption discrepancies.</p> Signup and view all the answers

    Which item is NOT listed as part of the checks to be conducted before passing the bills?

    <p>Energy source verification</p> Signup and view all the answers

    What should be done if the minimum charge exceeds actual energy consumption?

    <p>Inform the Chief Electrical Engineer and operating Department.</p> Signup and view all the answers

    What is the purpose of the time schedule established with the Accounts Department?

    <p>To achieve prompt payment for rebate eligibility.</p> Signup and view all the answers

    Which of the following should be analyzed for significant departures?

    <p>Each new bill compared to earlier ones</p> Signup and view all the answers

    What must be correctly indicated on the bill according to the agreement?

    <p>The payee's full particulars</p> Signup and view all the answers

    Which practice is NOT recommended regarding panel charges?

    <p>Cutting panel charges during peak usage</p> Signup and view all the answers

    What must be confirmed about the maximum demand computation for billing?

    <p>It follows agreed method and does not include temporary increases.</p> Signup and view all the answers

    If there is a significant change in billing amounts, what should happen?

    <p>Analyze the new bill against previous records.</p> Signup and view all the answers

    What aspect of the billing process should be clearly documented?

    <p>Jointly issued detailed instructions before passing bills.</p> Signup and view all the answers

    What precaution should be taken to avoid a leading power factor when using power factor correcting equipment?

    <p>Use switched capacitors judiciously.</p> Signup and view all the answers

    In the event of an unavoidable shut-down of traction supply, who should the reasons for the shut-down be communicated to?

    <p>The operating department for scheduling.</p> Signup and view all the answers

    What is necessary for the planning of power factor improvement capacitors at traction substations?

    <p>Prioritize substations with low power factor costs.</p> Signup and view all the answers

    What is the expected approach for maintenance shutdowns at substations to avoid total interruptions?

    <p>Ensure sufficient backup systems are always available.</p> Signup and view all the answers

    What should be included in the detailed operating instructions for grid substations?

    <p>A comprehensive guide for switching operations.</p> Signup and view all the answers

    What is the significance of maintaining traction voltage between 25 KV and 27.5 KV at feeding posts?

    <p>It ensures the reliability of the power supply.</p> Signup and view all the answers

    Which of the following actions is recommended to enhance the reliability of the power supply for traction?

    <p>Conducting periodic meetings with Supply Authorities.</p> Signup and view all the answers

    When should the traction load be treated as essential according to the recommendations?

    <p>At all times to prevent disconnection.</p> Signup and view all the answers

    What is the recommended maximum frequency range that should be maintained in the supply system for traction?

    <p>48.5 Hz to 51.5 Hz</p> Signup and view all the answers

    What must be done regarding periodic reviews of power supply interruptions?

    <p>Causes should be ascertained and reported at the Divisional level.</p> Signup and view all the answers

    What is the role of effective liaison between Railway and Supply Authorities?

    <p>To ensure continuity and reliability of power supply.</p> Signup and view all the answers

    What is a key factor that can negatively impact railway traffic with respect to power supply?

    <p>Inconsistent liaison with power supply authorities.</p> Signup and view all the answers

    What should be done if there is no specific Agreement with the Supply Authority regarding power supply for electric traction?

    <p>Take urgent action to finalize the Agreement</p> Signup and view all the answers

    What action should be taken when emergency working leads to a temporary increase in maximum demand?

    <p>Negotiate with Supply Authorities to ignore the increase</p> Signup and view all the answers

    The method agreed upon by the Central Electricity Authority for charging Railways for traction power is based on which criteria?

    <p>Simultaneous maximum demand of contiguous substations</p> Signup and view all the answers

    What is a primary goal when stipulating contract demand for each sub-station?

    <p>Avoiding unnecessary payments for minimum guarantees</p> Signup and view all the answers

    Which factor should not be considered when evaluating tariffs charged for electric traction?

    <p>Annual fixed costs associated with maintenance</p> Signup and view all the answers

    Ideal notice period for altering contract demand should be set at?

    <p>4 to 6 weeks</p> Signup and view all the answers

    What variation in tariff structures is observed among different state Electricity Boards for electric traction?

    <p>Some states use a simplified flat rate, others opt for complex structures</p> Signup and view all the answers

    What is a critical aspect of measuring maximum demand for billing at traction substations?

    <p>Recording simultaneous maximum demand in contiguous substations</p> Signup and view all the answers

    Which of the following statements about emergency working at traction sub-stations is inaccurate?

    <p>It mandates an immediate review of the contrast agreement</p> Signup and view all the answers

    What is a necessary step before passing the bills from the Supply Authorities?

    <p>Checking that the maximum demand computation aligns with the billing amount</p> Signup and view all the answers

    Which of the following actions should be taken if the minimum charge exceeds actual energy consumption?

    <p>Immediately contact the CEE and the operating Department for remedial action</p> Signup and view all the answers

    What is the main objective of establishing a time schedule for scrutinizing bills?

    <p>To ensure prompt payment for discounts and rebates related to usage</p> Signup and view all the answers

    Which aspect should not be included in the checklist for scrutinizing bills?

    <p>Verification of the contract duration with previous agreements</p> Signup and view all the answers

    When discrepancies in billing amounts occur, what should be the immediate course of action?

    <p>Investigate the reasons for significant departures compared to earlier bills</p> Signup and view all the answers

    What essential detail regarding billing must be clear as per the agreement?

    <p>The exact payee's details as stipulated in the agreement</p> Signup and view all the answers

    Which of the following is an important reason for conducting a thorough billing scrutiny?

    <p>To ensure that accurate energy consumption metrics are utilized</p> Signup and view all the answers

    What should be done if panel charges are levied incorrectly?

    <p>Carefully scrutinize and implement remedial measures to prevent recurrence</p> Signup and view all the answers

    What should be done with each new bill before passing it?

    <p>It should be compared with previous bills to understand significant changes</p> Signup and view all the answers

    What should local instructions include regarding the checking of bills?

    <p>Explicit directives on arithmetical checks and meter readings</p> Signup and view all the answers

    What is the method for calculating the total harmonic voltage distortion (Vn)?

    <p>$ rac{(V2^2 + V3^2 + V4^2 + ... + V13^2)}{V} imes 100$</p> Signup and view all the answers

    Under what condition can the Railway request testing of the meter for accuracy?

    <p>If accuracy is in doubt at any point of time</p> Signup and view all the answers

    What percentage of harmonic voltage distortion is allowed for the individual harmonic at the point of supply?

    <p>1% and 3% respectively for different conditions</p> Signup and view all the answers

    What should the billing figures be based on when two sets of meters are provided?

    <p>The average readings of the two sets of meters</p> Signup and view all the answers

    When should the monthly meter readings be taken?

    <p>On an agreed date each month jointly by both parties</p> Signup and view all the answers

    What additional information should be obtained during visits to grid sub-stations?

    <p>Daily maximum demand, power factor, and voltage variations</p> Signup and view all the answers

    What should be ensured regarding the tariff for traction?

    <p>It should be reviewed periodically with the SEB</p> Signup and view all the answers

    What is necessary for readings to be accepted for billing purposes?

    <p>They must be jointly recorded and initialed by both parties</p> Signup and view all the answers

    What action should be taken if the maximum demand computation for billing is incorrect?

    <p>Follow the stated procedure to confirm the accuracy</p> Signup and view all the answers

    What is a primary purpose of conducting harmonic analysis?

    <p>To assess compliance with voltage distortion limits</p> Signup and view all the answers

    Study Notes

    Power Supply for Traction

    • Single-phase 50 Hz power for electric traction is obtained from a 220/132/110/66 kV extra high voltage 3-phase grid system via step-down transformers.
    • Duplicate 2-phase feeders are run from the nearest grid substation.
    • A schematic diagram of the traction substation and feeding post is provided (Fig 1.01).
    • The 25 kV single-phase conventional system is described in Chapter 2 of Volume I. This system is used on Indian Railways.

    Liaison with Power Supply Authorities

    • Effective liaison between railway and supply authorities is crucial for reliable power supply.
    • Periodic meetings at various levels should be established.
    • Traction voltage (25-27.5 kV) and frequency (48.5-51.5 Hz) must be maintained.
    • Traction load is considered essential and should not be disconnected or reduced.
    • Periodic reviews of power supply interruptions should occur at the divisional level.
    • An agreement between the railway and supply authority is needed before power supply is initiated.
    • Temporary increases in maximum demand at substations due to feeding from adjacent stations should be ignored by supply authorities for billing purposes.
    • Railways should be charged for traction power based on the simultaneous maximum demand of serviced substations.

    Typical Traction Power Supply Arrangement

    • Diagram (Figure 1.01) illustrates the typical arrangement.
    • The diagram shows incoming high voltage supply, transformers, circuit breakers, lightning arresters, and other components for 25 kV supply.

    Power Tariff for Traction

    • Energy costs are significant in electric traction.
    • Tariffs vary between simple flat rates and complex structures.
    • Contract demand for each substation should be stipulated relative to expected maximum demand.
    • Avoid penal charges for exceeding or insufficient contract demand.
    • Short notice periods for contract demand alterations are preferable.
    • Key tariff parameters to minimize energy bill include maximum demand charge (Rs/KVA/month), energy charge (paise/kWh), fuel adjustment charges (FAC).
    • Penalty for low power factor.
    • Billing demand should be the higher of the actual maximum demand (MD) or a certain percentage of the contract demand.
    • Excess over contract demand results in higher tariffs.
    • Minimum guarantee clauses exist for power supply.
    • Harmonic voltage distortion limits are also specified.

    Monthly Meter Readings

    • Monthly meter readings should be jointly taken by representatives from both railway and supply authorities.
    • Initialed meter cards and printouts of maximum demand data are needed.
    • Supervisory officials should collect data on maximum demand, power factor, load factor, etc.

    Shut-downs of Traction Supply Planning

    • Pre-planning of shutdowns and giving adequate notice to the Supply Authorities is crucial.
    • Multiple EHV feeders and transformers at substations are preferred to avoid complete shutdown.

    Statistical Data Regarding Energy Consumption

    • Divisional offices should record monthly energy consumption data (e.g., kWh, KVA).
    • Power factor, monthly average load factor, payments, and other factors are also part of the data required to be maintained.

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    Related Documents

    Indian Railways AC Traction Manual PDF

    Description

    This quiz explores the power supply systems used in electric traction for Indian Railways, specifically the 25 kV single-phase system. It covers the connection with extra high voltage grids, the role of step-down transformers, and essential liaison with power supply authorities for maintaining traction voltage and frequency. Understand the importance of these systems for reliable railway operations.

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