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Questions and Answers
What is a significant advantage of composite insulators compared to conventional porcelain insulators?
What is a significant advantage of composite insulators compared to conventional porcelain insulators?
Which materials are commonly used to make the core of composite insulators?
Which materials are commonly used to make the core of composite insulators?
What characteristic of conventional porcelain insulators makes them susceptible to damage?
What characteristic of conventional porcelain insulators makes them susceptible to damage?
How is moisture prevented from entering the composite insulator?
How is moisture prevented from entering the composite insulator?
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Which elastomer is mentioned as a material used in the sheds of composite insulators?
Which elastomer is mentioned as a material used in the sheds of composite insulators?
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What problem associated with conventional porcelain insulators does not occur with composite insulators?
What problem associated with conventional porcelain insulators does not occur with composite insulators?
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Why are the end fittings of composite insulators usually crimped to the core?
Why are the end fittings of composite insulators usually crimped to the core?
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What type of tests have composite insulators exhibited excellent performance in?
What type of tests have composite insulators exhibited excellent performance in?
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What is a disadvantage of the glazed surface of conventional porcelain insulators?
What is a disadvantage of the glazed surface of conventional porcelain insulators?
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Which organization is working towards the introduction of composite insulators?
Which organization is working towards the introduction of composite insulators?
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What is a main advantage of using dry cast resin transformers?
What is a main advantage of using dry cast resin transformers?
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Which type of relay is currently used for distance protection of the overhead equipment?
Which type of relay is currently used for distance protection of the overhead equipment?
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What is a characteristic of the new static type distance protection relay developed by RDSO?
What is a characteristic of the new static type distance protection relay developed by RDSO?
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How long can the time settings be adjusted in the second and third zones of the new relay?
How long can the time settings be adjusted in the second and third zones of the new relay?
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What is the main disadvantage of the electromechanical relay mentioned in the content?
What is the main disadvantage of the electromechanical relay mentioned in the content?
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What does the first zone of the new relay typically cover?
What does the first zone of the new relay typically cover?
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What is the purpose of the under voltage relay at the SP?
What is the purpose of the under voltage relay at the SP?
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What characteristic do the first two zones of the static distance protection relay have?
What characteristic do the first two zones of the static distance protection relay have?
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What is a feature of the third zone of the new static relay?
What is a feature of the third zone of the new static relay?
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What is a current limitation regarding the static relays with parallelogram characteristics?
What is a current limitation regarding the static relays with parallelogram characteristics?
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What is the typical spacing of auto-transformers in the system design?
What is the typical spacing of auto-transformers in the system design?
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What is the standard capacity of the auto-transformers mentioned in the content?
What is the standard capacity of the auto-transformers mentioned in the content?
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Which of the following is NOT a parameter proposed to be monitored on the pantograph?
Which of the following is NOT a parameter proposed to be monitored on the pantograph?
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What is one of the proposed features of the on-board computer in the trailer type car?
What is one of the proposed features of the on-board computer in the trailer type car?
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What type of vehicle is suitable for propulsion both on road and track?
What type of vehicle is suitable for propulsion both on road and track?
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Which advantage is associated with dry type cast resin transformers compared to oil filled ones?
Which advantage is associated with dry type cast resin transformers compared to oil filled ones?
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Which measurement is taken on the OHE?
Which measurement is taken on the OHE?
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What is an essential feature of the transportable self-propelled trolley?
What is an essential feature of the transportable self-propelled trolley?
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What is a key measurement related to the quality of current collection on the pantograph?
What is a key measurement related to the quality of current collection on the pantograph?
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Which of the following parameters is related to assessing the state of the contact wire?
Which of the following parameters is related to assessing the state of the contact wire?
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What is the main purpose of using Wood-bridge/V-connected transformers in the traction substations?
What is the main purpose of using Wood-bridge/V-connected transformers in the traction substations?
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What voltage does the incoming extra high voltage power get stepped down to in the traction substation?
What voltage does the incoming extra high voltage power get stepped down to in the traction substation?
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How is the 25 kV supply reference established in the traction power supply system?
How is the 25 kV supply reference established in the traction power supply system?
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What is the function of a short neutral section in the overhead equipment (OHE)?
What is the function of a short neutral section in the overhead equipment (OHE)?
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What determines the capacity and spacing of auto-transformers in the system?
What determines the capacity and spacing of auto-transformers in the system?
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Which component is connected to the overhead catenary wires in the auto-transformer arrangement?
Which component is connected to the overhead catenary wires in the auto-transformer arrangement?
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Where is a sectioning and paralleling post typically located in relation to traction substations?
Where is a sectioning and paralleling post typically located in relation to traction substations?
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What is the arrangement at the Feeding Post generally similar to?
What is the arrangement at the Feeding Post generally similar to?
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How many phases do the duplicate feeders from the grid sub-station to the traction substation typically consist of?
How many phases do the duplicate feeders from the grid sub-station to the traction substation typically consist of?
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What is an essential feature of the auto-transformer feeding system regarding transformer placement?
What is an essential feature of the auto-transformer feeding system regarding transformer placement?
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What is a primary characteristic of composite insulators that distinguishes them from conventional porcelain insulators?
What is a primary characteristic of composite insulators that distinguishes them from conventional porcelain insulators?
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Which of the following materials is specifically mentioned as being used for the sheds of composite insulators?
Which of the following materials is specifically mentioned as being used for the sheds of composite insulators?
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How do composite insulators prevent moisture ingress?
How do composite insulators prevent moisture ingress?
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Which disadvantage of traditional porcelain insulators is effectively mitigated by composite insulators?
Which disadvantage of traditional porcelain insulators is effectively mitigated by composite insulators?
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What specialized feature allows composite insulators to perform well in pollution tests?
What specialized feature allows composite insulators to perform well in pollution tests?
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What aspect of the interface between the core and the sheds in composite insulators is crucial for their performance?
What aspect of the interface between the core and the sheds in composite insulators is crucial for their performance?
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Which of the following statements regarding the settings of the discussed relay is accurate?
Which of the following statements regarding the settings of the discussed relay is accurate?
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Why is the interface between the core and sheds of composite insulators sealed?
Why is the interface between the core and sheds of composite insulators sealed?
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Which scenario best highlights the significance of composite insulators in modern applications?
Which scenario best highlights the significance of composite insulators in modern applications?
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What is the primary composite material for the core of composite insulators mentioned in the context?
What is the primary composite material for the core of composite insulators mentioned in the context?
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What specific upward force is measurable on the pantograph?
What specific upward force is measurable on the pantograph?
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Which of the following describes a benefit of dry type cast resin transformers?
Which of the following describes a benefit of dry type cast resin transformers?
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What is one of the functions of the on-board computer in the proposed trailer type car?
What is one of the functions of the on-board computer in the proposed trailer type car?
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Which parameter is NOT monitored on the overhead equipment (OHE)?
Which parameter is NOT monitored on the overhead equipment (OHE)?
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What specific aspect of the transportable self-propelled trolley is highlighted?
What specific aspect of the transportable self-propelled trolley is highlighted?
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What type of vehicle is suitable for dual propulsion on road and track?
What type of vehicle is suitable for dual propulsion on road and track?
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Which parameter is monitored for the quality of current collection on the OHE?
Which parameter is monitored for the quality of current collection on the OHE?
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What provides an essential advantage of dry type transformers over oil-filled transformers?
What provides an essential advantage of dry type transformers over oil-filled transformers?
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Which movement is measured regarding the pantograph?
Which movement is measured regarding the pantograph?
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What is the typical spacing of auto-transformers in the system design mentioned?
What is the typical spacing of auto-transformers in the system design mentioned?
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What is the primary risk eliminated by using dry cast resin transformers in the context of theft?
What is the primary risk eliminated by using dry cast resin transformers in the context of theft?
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What characteristic of the electromechanical relay presents a potential problem in distance protection?
What characteristic of the electromechanical relay presents a potential problem in distance protection?
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The static type distance protection relay developed by RDSO uses which type of characteristic for its first two zones?
The static type distance protection relay developed by RDSO uses which type of characteristic for its first two zones?
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What is the purpose of introducing a time delay in the second and third zones of the static distance relay?
What is the purpose of introducing a time delay in the second and third zones of the static distance relay?
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Which statement describes the third zone of the static distance protection relay?
Which statement describes the third zone of the static distance protection relay?
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Why are static relays with parallelogram characteristics currently imported?
Why are static relays with parallelogram characteristics currently imported?
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What is the maximum distance the first zone of the static relay is designed to cover?
What is the maximum distance the first zone of the static relay is designed to cover?
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What issue is anticipated with the increase in traffic and traction power transformer capacity?
What issue is anticipated with the increase in traffic and traction power transformer capacity?
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What key design aspect distinguishes the static relay from its electromechanical counterpart?
What key design aspect distinguishes the static relay from its electromechanical counterpart?
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What function does the under voltage relay at the SP serve in the protection scheme?
What function does the under voltage relay at the SP serve in the protection scheme?
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What is the purpose of using Wood-bridge/V-connected transformers in the traction substations?
What is the purpose of using Wood-bridge/V-connected transformers in the traction substations?
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What is the incoming extra high voltage power stepped down to in the traction substation?
What is the incoming extra high voltage power stepped down to in the traction substation?
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How is the 25 kV supply related to the rail potential in the traction power supply system?
How is the 25 kV supply related to the rail potential in the traction power supply system?
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What arrangement is typical at the Sectioning and Paralleling Post (SP)?
What arrangement is typical at the Sectioning and Paralleling Post (SP)?
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What determines the spacing and capacity of the auto-transformers in the system?
What determines the spacing and capacity of the auto-transformers in the system?
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What is a notable feature of the auto-transformer post in the 2x25 kV system?
What is a notable feature of the auto-transformer post in the 2x25 kV system?
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What is the significance of having duplicate feeders from the grid sub-station to the traction substation?
What is the significance of having duplicate feeders from the grid sub-station to the traction substation?
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Where is the feeder wire supported in relation to the overhead contact/catenary wire?
Where is the feeder wire supported in relation to the overhead contact/catenary wire?
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In conditions where the grid system capacity is insufficient, what might happen in the traction substations?
In conditions where the grid system capacity is insufficient, what might happen in the traction substations?
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What is the function of cut-in insulators at the feeder wire?
What is the function of cut-in insulators at the feeder wire?
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Study Notes
2x25 kV Auto-Transformer Feed System
- Incoming power supply scheme mirrors a 25 kV feed system, drawing from the nearest grid substation (132 kV or 220 kV, two-phase).
- Loads are higher (2-3 times) than 25 kV systems, requiring Wood-bridge/V-connected transformers at traction substations to manage imbalances within acceptable limits. Grid system capacity needs to be sufficient.
- Power is received at the traction substation by stepping down the extra-high voltage to 2x25 kV via a traction power transformer.
- 2x25 kV supply is fed to an auto-transformer. One terminal connects to overhead catenary wires, the other to a feeder wire running parallel to the overhead wires (supported from super masts).
- The auto-transformer's midpoint is connected to the rail, creating a 25 kV supply relative to the rail potential for traction.
- Auto-transformer capacity and spacing are dictated by section traffic patterns.
- Distribution is similar to 25 kV conventional systems for the feeding post (FP) and sectioning/paralleling post (SP).
- Auto-transformer posts are spaced every 15 km, with a 2 MVA capacity. Current distribution is detailed in Figure 11.02.
Distribution of Traction Power Supply
- Feeding Post (FP) arrangements mirror 25 kV conventional systems.
- Sectioning and Paralleling Post (SP) designs are similar to 25 kV conventional SSP systems. Neutral sections are part of the overhead equipment (OHE).
- Short neutral sections are provided in the OHE opposite feeding posts, and mid-way between adjacent substations to provide grounding.
- Feeder wire neutral sections are also included, using cut-in insulators.
Overhead Equipment
- OHE is similar to 25 kV systems, except for an additional feeder wire running parallel to the overhead contact wire.
- This feeder wire is insulated at 25 kV from the steel structure and at 2x25 kV from the traction OHE.
Protective Systems
- Include relays and protection devices for transformer protection; specific relays are designed for 2x25 kV AT feed systems; these include distance relays, AC failure detection devices, and over-current relays.
OHE Recording-cum-Test Car
- Crucial to maintain precise overhead equipment geometry for reliable current collection (height, stagger, contact wire conditions).
- Manual monitoring is prone to inaccuracies; a mechanized monitoring system is needed.
- Increased freight/passenger traffic and higher train speeds necessitate evaluating existing OHE and pantograph systems for improvements.
- A dedicated Overhead Equipment Recording cum Test Car is in development to measure and record OHE and pantograph parameters under both static and dynamic conditions (speeds up to 200 km/h).
Transformer and Auxiliary Transformer
- Conventional oil-filled transformers require maintenance; dry-type cast resin transformers are more reliable and maintenance-free.
- Dry-type transformers eliminate fire and explosion risks.
Static Distance Protection Relay
- Electromechanical relays, prone to tripping on normal overloads, are less effective in current schemes.
- Static distance protection relay (3-zone) with adjustable time-settings are more advanced.
- This relay uses a lenticular characteristic.
- This relay can be used as a method for backup protection in case of feed extension.
- An alternative is a static relay with a parallelogram characteristic; this is being developed indigenously.
Composite Insulators
- Conventional porcelain insulators have limited impact resistance, break easily, and are not hydrophobic.
- Composite insulators (porcelain or resin bonded glass fiber with elastomeric/plastic sheds) offer improved impact resistance and eliminate moisture ingress, making them more reliable.
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Description
This quiz explores the 2x25 kV auto-transformer feed system used for traction supply. It covers the incoming power supply scheme, transformer management, and distribution patterns necessary to maintain efficient rail operations. Test your understanding of these critical concepts!
