Track Circuit Broken Rail Detection via Dual Relay Segmentation
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Solution Overview
Problem
Prior art railroad track circuits fail to accurately detect broken rails due to sneak paths caused by negative return cross-bonding in electrified territories, leading to false de-energization and potential hazardous situations.
Innovation Solution
The use of two track relays with unique terminal connections, where each relay has a positive and negative track terminal and two local terminals, connected in a series arrangement to prevent sneak paths from interfering with the detection of broken rails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If negative return cross-bonding is applied between parallel tracks in electrified territory, then train propulsion current can be returned efficiently, but sneak paths are created that prevent accurate broken rail detection
Solution Approach 1:
The track circuit is segmented into two separate detection paths using two track relays. Each relay monitors a different electrical path through the rails, allowing the system to distinguish between current flowing through a intact rail versus current finding an alternate path through cross-bonds when a rail is broken. This segmentation enables accurate broken rail detection despite the presence of cross-bonding for propulsion current return.
Solution Approach 2:
Two track relays are introduced as intermediary devices that act as mediators between the track circuit and the detection system. These relays are uniquely arranged to block sneak paths caused by cross-bonding while still allowing legitimate track circuit current to pass through, thereby enabling accurate broken rail detection in electrified territory with cross-bonding.
2Device complexity
If a single track relay is used in prior art track circuits, then the circuit is simple, but sneak paths cause false de-energization and mask broken rail conditions
Solution Approach 1:
The single track relay is segmented into two separate track relays with unique terminal connections. This segmentation creates two independent detection paths that can identify when current is diverted through sneak paths caused by cross-bonding, thereby reliably detecting broken rails even in the presence of such interference paths.
Solution Approach 2:
Each track relay is given a specific local function through unique terminal connections. The first relay monitors current through one set of terminals while the second relay monitors through different terminals, allowing each relay to detect specific conditions related to rail integrity while ignoring sneak paths that affect only certain paths.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures accurate detection of broken rails by ensuring that the track circuit remains de-energized even in the presence of sneak paths, thereby ensuring safe train operations.
Implementation Method 1
A track circuit includes the two running rails 1. A local power supply feeds an energy source 2 connected to one end of a block isolated by insulated rail joints 3. A relay or equivalent device 4 is connected to the end opposite the energy source 2. Track circuit current 5 flows from the energy source 2 through the rails 1 to the track relay 4, thereby energizing it.
Data Source
AI summary
A railroad track circuit providing for the positive detection of broken rails despite the presence of factors that would otherwise preclude such detection is disclosed. These factors include sneak paths arising from the presence of negative return cross-bonding as applied between parallel tracks in electrified territory. Broken rail detection is ensured through the provision of two track relays, or devices that function as track relays, uniquely arranged so as to render the track circuit immune from these factors.