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Questions and Answers
What should be checked to ensure the gas supply to the system is adequate?
What should be checked to ensure the gas supply to the system is adequate?
Which maintenance action is NOT required for the interrupting chamber of a vacuum circuit breaker?
Which maintenance action is NOT required for the interrupting chamber of a vacuum circuit breaker?
Which factor is essential to check when ensuring the operating mechanism is functioning properly?
Which factor is essential to check when ensuring the operating mechanism is functioning properly?
What should be done with absorbent materials during maintenance?
What should be done with absorbent materials during maintenance?
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How should the working of the pressure gauge be confirmed?
How should the working of the pressure gauge be confirmed?
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What is the voltage rating of the lead acid batteries used for control in traction sub-stations?
What is the voltage rating of the lead acid batteries used for control in traction sub-stations?
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Which of the following is a feature of mains operated battery chargers?
Which of the following is a feature of mains operated battery chargers?
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What should be performed on the operating mechanism to prevent rust?
What should be performed on the operating mechanism to prevent rust?
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In remote control equipment, what should be considered regarding battery placement?
In remote control equipment, what should be considered regarding battery placement?
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What should inspecting officials do to avoid neglect of installations during inspections?
What should inspecting officials do to avoid neglect of installations during inspections?
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What is recommended to do if schedules for new equipment have not been established?
What is recommended to do if schedules for new equipment have not been established?
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What must be done before commencing work near live equipment?
What must be done before commencing work near live equipment?
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What is one of the actions to prevent unauthorized interference at substations?
What is one of the actions to prevent unauthorized interference at substations?
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Which of the following is a recommended maintenance schedule for circuit breakers?
Which of the following is a recommended maintenance schedule for circuit breakers?
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What additional context should be considered while carrying out maintenance work?
What additional context should be considered while carrying out maintenance work?
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Which type of circuit breakers have specific schedules mentioned in the Annexure?
Which type of circuit breakers have specific schedules mentioned in the Annexure?
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What should be included in the maintenance schedule for new equipment?
What should be included in the maintenance schedule for new equipment?
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What aspect of inspections is emphasized for maintaining quality?
What aspect of inspections is emphasized for maintaining quality?
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What is crucial for employees when they are near unattended substations?
What is crucial for employees when they are near unattended substations?
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What should be done if insulators are badly chipped?
What should be done if insulators are badly chipped?
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What action should be taken if the silica-gel breather appears pink?
What action should be taken if the silica-gel breather appears pink?
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What is the first step in maintaining traction transformers?
What is the first step in maintaining traction transformers?
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What should be checked for damage in traction transformers?
What should be checked for damage in traction transformers?
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Which material can be used to make minor chippings on insulators impervious to moisture?
Which material can be used to make minor chippings on insulators impervious to moisture?
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What should be done if there is oil leakage from the transformer?
What should be done if there is oil leakage from the transformer?
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What action should be taken if a battery is not in a fully charged condition?
What action should be taken if a battery is not in a fully charged condition?
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What is required to ensure a circuit breaker's control box is properly maintained?
What is required to ensure a circuit breaker's control box is properly maintained?
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What should be checked specifically on the low voltage side for potential transformers (PTs)?
What should be checked specifically on the low voltage side for potential transformers (PTs)?
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During quarterly maintenance, what should be noted regarding the battery charger?
During quarterly maintenance, what should be noted regarding the battery charger?
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What should be ensured regarding the weather-proof gaskets in the circuit breaker control box?
What should be ensured regarding the weather-proof gaskets in the circuit breaker control box?
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How should the oil level in equipment be rectified?
How should the oil level in equipment be rectified?
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What must be measured and recorded for auxiliary transformers during maintenance?
What must be measured and recorded for auxiliary transformers during maintenance?
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How often should the mechanism of circuit breakers be operated manually?
How often should the mechanism of circuit breakers be operated manually?
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What should be checked on booster transformers concerning earthing connections?
What should be checked on booster transformers concerning earthing connections?
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What is the primary responsibility of the Senior Section Engineer in Power Supply Installations?
What is the primary responsibility of the Senior Section Engineer in Power Supply Installations?
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Which of the following is NOT a duty of the Senior Section Engineer?
Which of the following is NOT a duty of the Senior Section Engineer?
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What should the Senior Section Engineer do in the event of equipment breakdowns?
What should the Senior Section Engineer do in the event of equipment breakdowns?
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Which method is important for ensuring the reliability of power supply?
Which method is important for ensuring the reliability of power supply?
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What is crucial for the maintenance of protective relays?
What is crucial for the maintenance of protective relays?
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How should the Senior Section Engineer manage spare parts and stores?
How should the Senior Section Engineer manage spare parts and stores?
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What is a key responsibility in training the staff under the Senior Section Engineer's control?
What is a key responsibility in training the staff under the Senior Section Engineer's control?
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What is a significant risk associated with high voltage equipment due to excessive moisture in oil?
What is a significant risk associated with high voltage equipment due to excessive moisture in oil?
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What type of circuit breaker is now standardized to overcome maintenance limitations of oil-type breakers?
What type of circuit breaker is now standardized to overcome maintenance limitations of oil-type breakers?
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Which property of SF6 gas contributes to its effectiveness in circuit breakers?
Which property of SF6 gas contributes to its effectiveness in circuit breakers?
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What by-product is produced from arcing in SF6 circuit breakers?
What by-product is produced from arcing in SF6 circuit breakers?
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What is a common maintenance issue with minimum oil type circuit breakers?
What is a common maintenance issue with minimum oil type circuit breakers?
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What characteristic of SF6 gas minimizes the impact of its decomposition after long periods of arcing?
What characteristic of SF6 gas minimizes the impact of its decomposition after long periods of arcing?
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What maintenance instruction is critical for circuit breakers and interrupters?
What maintenance instruction is critical for circuit breakers and interrupters?
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What is essential to ensure the proper functioning of the control panel?
What is essential to ensure the proper functioning of the control panel?
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Which check is mandatory for the interrupters during maintenance?
Which check is mandatory for the interrupters during maintenance?
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What should be verified regarding the battery charger during routine checks?
What should be verified regarding the battery charger during routine checks?
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In the context of ensuring the soundness of earth connections, what must be checked?
In the context of ensuring the soundness of earth connections, what must be checked?
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Which aspect is crucial when checking remote control equipment?
Which aspect is crucial when checking remote control equipment?
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What is the maximum acceptable pressure for gas supply during maintenance?
What is the maximum acceptable pressure for gas supply during maintenance?
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Which action is critical when renewing the absorbent in the interrupting unit?
Which action is critical when renewing the absorbent in the interrupting unit?
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Which of the following steps is NOT essential for the operating mechanism maintenance check?
Which of the following steps is NOT essential for the operating mechanism maintenance check?
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Which condition must be fulfilled for the maintenance of vacuum circuit breakers?
Which condition must be fulfilled for the maintenance of vacuum circuit breakers?
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For lead acid batteries in traction sub-stations, how should their capacity be correlated with charging systems?
For lead acid batteries in traction sub-stations, how should their capacity be correlated with charging systems?
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What is the voltage range for lead acid batteries used at switching stations?
What is the voltage range for lead acid batteries used at switching stations?
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What should be checked in the pneumatic system as part of the operating mechanism maintenance?
What should be checked in the pneumatic system as part of the operating mechanism maintenance?
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What is a common practice regarding battery chargers in traction sub-stations and switching stations?
What is a common practice regarding battery chargers in traction sub-stations and switching stations?
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What should be done with the connections of control circuit wires during maintenance?
What should be done with the connections of control circuit wires during maintenance?
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What is the approximate cell voltage at the end of a full charge for new batteries receiving a charge at a 10-hour rate?
What is the approximate cell voltage at the end of a full charge for new batteries receiving a charge at a 10-hour rate?
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Which factor does NOT influence the voltage of a battery cell at the end of a charge?
Which factor does NOT influence the voltage of a battery cell at the end of a charge?
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At what cell voltage level should a battery NEVER be discharged below?
At what cell voltage level should a battery NEVER be discharged below?
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What color should the active material in the positive plates of a healthy cell be after more than 12 months of use?
What color should the active material in the positive plates of a healthy cell be after more than 12 months of use?
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What indicates a weak cell when inspecting battery plates?
What indicates a weak cell when inspecting battery plates?
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What is the primary cause of noticeable drop in terminal voltage in lead-acid cells?
What is the primary cause of noticeable drop in terminal voltage in lead-acid cells?
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During battery maintenance, how should flakes of brown scale detached from positive plates be handled?
During battery maintenance, how should flakes of brown scale detached from positive plates be handled?
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What is the relationship between the voltage of a cell and its state of charge?
What is the relationship between the voltage of a cell and its state of charge?
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What color indicates the active material of healthy negative plates according to their age?
What color indicates the active material of healthy negative plates according to their age?
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What should be done to voltmeters when not in use to ensure accuracy?
What should be done to voltmeters when not in use to ensure accuracy?
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What color of deposits indicates that a lead-acid battery is in a discharged condition?
What color of deposits indicates that a lead-acid battery is in a discharged condition?
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What should be done immediately if excessive shedding of active material from positive plates is noticed?
What should be done immediately if excessive shedding of active material from positive plates is noticed?
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Which inspection method is recommended for the inter-cell connectors of a battery?
Which inspection method is recommended for the inter-cell connectors of a battery?
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When a weak cell is found, what is the immediate action that should be taken?
When a weak cell is found, what is the immediate action that should be taken?
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What preventive measure can be applied to inter-cell connectors to avoid corrosion?
What preventive measure can be applied to inter-cell connectors to avoid corrosion?
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Which certification should specialist staff hold for the maintenance of protective relays?
Which certification should specialist staff hold for the maintenance of protective relays?
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What is the recommended action if copper inter-row connectors show signs of corrosion?
What is the recommended action if copper inter-row connectors show signs of corrosion?
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What should each Supervisor maintain regarding protective relays?
What should each Supervisor maintain regarding protective relays?
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What should be done if all cells in a battery show whitish deposits?
What should be done if all cells in a battery show whitish deposits?
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What type of paint should be applied to exposed copper work in the battery area?
What type of paint should be applied to exposed copper work in the battery area?
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Study Notes
Sub-Stations and Switching Stations
- This chapter is divided into four sections: Organization, Operation of sub-stations, Guiding Notes on Maintenance, and a recommended schedule for power supply equipment maintenance.
- Section I covers the organization and duties of Senior Section Engineer (Power Supply Installations).
- Section II covers important points relating to the operation of transformers and protective devices.
- Section III covers important points for the maintenance of power supply equipment.
- Section IV provides a recommended schedule for power supply equipment maintenance.
- Appendices to the volume include documents on the Earthing of Power Supply Installations, Relay Setting at Traction Substations and Switching Posts, Maintenance Depots, Tools and Plants with Transport Facilities, and Specifications and Drawings for Railway Electric Traction issued by RDSO.
- Divisional setup of senior subordinates can be arranged on two types of patterns: Territorial basis and functional basis.
- Duties of Senior Section Engineer (Power Supply Installations) include ensuring safe and efficient operation and maintenance of traction power supply installations, including substations, switching stations, booster transformers, and auxiliary transformers in their jurisdiction.
- The Senior Section Engineer must be conversant with equipment ratings, power demand trends, and correct maintenance methods
- Responsibilities include supervision of maintenance, coordination with other engineers to ensure reliable power supply, and readiness to deal with breakdowns.
- Staff training and adherence to safety regulations are crucial aspects of the role.
- Spare parts and tool inventory management, and periodic verification are important for the Senior Section Engineer.
- Sub-stations and switching stations have to be maintained for continuous power supply, with redundancy to support critical equipment failures in the system.
- An inspection book and log book are maintained at every sub-station to record observations by supervisory officials during periodic inspections.
- Oil temperatures, ambient temperatures, currents, and voltage measurements are recorded to detect any anomalies for immediate remedial action.
- Traction transformers have overload ratings, such as 50% for 15 minutes and 100% for 5 minutes.
- Maximum permissible temperature rises for windings and oil under various overload capacities are determined by resistance and thermometer methods.
- Tap settings on traction transformers are managed using off-load changers that enable local or remote control with steps of 5% from +10% to -15%.
- Daily 24-hour voltage recordings are taken to decide on the correct tap setting and ensure that the OHE voltage never falls below 19 kV.
- Oil purification is crucial to remove contaminants like water, carbon deposits, dirt, sludge, dissolved moisture, and gases to maintain dielectric strength.
- Specific tests are performed on transformer oil, such as breakdown voltage, acidity, crackle test, and moisture, to quality control levels.
- Installation resistance checks are made while equipment is drying out of oil.
- Protective devices, such as alarm and trip contacts, are vital for safe operation of traction transformers by detecting excessive temperature and overload levels.
- Differential protection and Buchholz relays help in detecting internal faults in transformers to help with quick correction.
Guiding Notes on Maintenance
- Maintenance of traction assets needs to minimize outages and maintain safety.
- Recommendations from OEMs and guidelines from RDSO are important in defining scope and schedule for maintenance.
- A schedule of tightening torque for fasteners is provided.
- Condition Monitoring of transformers and associated equipment is vital.
- Deterioration of insulation and oil in oil filled equipment (e.g., transformers) due to thermo-chemical reactions with heat, moisture, and oxygen impacts efficiency, and is monitored.
- Dissolved gas analysis (DGA) helps assess the condition of insulation, detect incipient faults, and evaluate status of oil.
Overhaul of Transformers
- Transformers can be overhauled either as preventative care or due to internal faults.
- All overhauls should be done in the Central Repair Shop.
- Procedures for draining oil, removing leads, and safely removing the core.
- Cleaning of the transformer tank, and repairs to the gasket.
- Ensuring all work tools, cables etc are accounted for during these repairs.
- Procedures for assessing the cause of any internal faults.
- Detailed procedure for safely removing the core, and steps to follow if one coil has burnt out are outlined.
Circuit Breakers and Interrupters
- Various types of circuit breakers and interrupters are discussed (e.g., SF6 type, Vacuum type, Oil type)
- Maintenance guidelines are given for different types of circuit breakers.
Lead Acid Batteries
- Lead-acid batteries are vital for power supply installations and require regular maintenance.
- Their location (e.g., traction sub-stations, switching stations, remote control equipment) is specified.
- Guidelines on maintenance involve checking the general battery room condition, electrolyte specific gravity, charging current, cell voltage, plate and deposit conditions, and inter-cell connectors.
- Specific gravity values for testing are described.
- Important notes regarding safe working conditions in the battery room are included.
Fortnightly Maintenance.
- A complete general inspection of the sub-station, focusing on cleanliness and drainage are performed regularly.
Monthly maintenance.
- Visual inspection of all earth connections to ensure proper operation and that components are properly tightened.
- Oil levels, and other relevant component checks are performed.
Quarterly Maintenance
- Testing transformer oil for BDV, Acidity or crackle related issues is performed.
- Checks on all alarm and protection devices are performed
Half yearly maintenance.
- An inspection is carried out to ensure that the grid networks have not changed.
Yearly Maintenance
- Sub-station fences, lighting, and doors are inspected
Data Collection and Analysis
- DGA should be done on a regular basis.
- Dissolved gas analysis is performed on the oil from the transformer to check on its internal condition.
- Results are stored and analyzed for trends or faults.
Physical Properties of SF6 Gas
- Important physical characteristics of SF6 gas are listed, such as molecular weight, melting point/sublimation point, critical temperature/pressure, critical density, dielectric constant, thermal conductivity at 30°C, solubility density at different temperatures.
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Description
This quiz covers key concepts from the chapter on Sub-Stations and Switching Stations, including organization, operation, and maintenance of power supply equipment. It also highlights the responsibilities of Senior Section Engineers and provides guidelines for effectively managing power supply installations. Delve into important maintenance schedules and appendices that support railway electric traction.
