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Examoogle • User • info@examoogle.com • EE-2024-8821
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Sub-sectioning and Paralleling posts are provided at a distance of
10 – 15 km
10 – 25 km
10 – 50 km
10 – 65 km
10 – 15 km
Sub-sectioning and paralleling posts (SSP) are critical elements in 25 kV AC single-phase traction systems designed to maintain voltage stability and minimize interference. They are typically spaced at intervals of 10 to 15 km to provide effective sectioning and paralleling of the overhead equipment (OHE) for maintenance and fault isolation.
Sub-sectioning and paralleling posts (SSP) are critical elements in 25 kV AC single-phase traction systems designed to maintain voltage stability and minimize interference. They are typically spaced at intervals of 10 to 15 km to provide effective sectioning and paralleling of the overhead equipment (OHE) for maintenance and fault isolation.
Vdrop=I⋅Zline — Represents the voltage drop along the traction line, which SSPs help to minimize by reducing effective impedance Zline.
The OHE is divided into electrical sections to allow for sectioning during maintenance or a catenary break. Paralleling posts connect the OHE of parallel tracks, which helps in reducing the overall impedance of the system and improves voltage regulation at the pantograph. By paralleling the conductors, the current load is distributed, and potential voltage drops along the feeding line are mitigated.
SSPs prevent the spread of faults from one electrical section to another.
They facilitate the maintenance of OHE by allowing isolation of specific subsections.
Improvement in current distribution occurs by paralleling the OHE of multiple tracks.
Standard Indian Railways practice sets this distance to 10-15 km based on load and voltage drop requirements.
Improved voltage regulation
Enhanced sectionalization for fault isolation
Balanced load sharing between parallel tracks
High initial infrastructure cost
Complex maintenance of high-voltage switching equipment
25 kV AC Electric Traction Systems
High-speed railway electrification
Feeding posts are located near substations, whereas SPs (Sectioning Posts) or SSPs are located between substations.
Option B, C, and D describe much longer distances that would lead to unacceptable voltage drops and difficulty in fault isolation for standard 25 kV AC systems.
A is correct — Sub-sectioning and paralleling posts are placed at 10 – 15 km intervals to ensure system reliability and efficient maintenance.
Always remember that in AC traction, spacing is dictated by both the voltage drop limit and the need for frequent isolation points to minimize train service disruption during OHE maintenance.