Rail-to-Ground Voltage Control to Prevent Distant Overvoltage

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Solution Overview

Problem

Conventional rail-to-ground voltage suppression systems fail to prevent excessive rail-to-ground voltage fluctuations from spreading along the entire train line, leading to secondary generation of excessive voltages at distant locations from the voltage control device.

Innovation Solution

A rail-to-ground voltage suppression system that includes a voltage control device and rail-to-ground voltage acquisition devices, which work together to detect and control voltage fluctuations, ensuring that the rail-to-ground voltage remains within a predetermined range across the entire train line.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a short circuit switch is activated to equalize potential between rail and ground, then rail-to-ground voltage at the activated position is suppressed, but voltage fluctuation spreads along the entire train line causing excessive voltage at distant locations

Engineering Contradiction:
Improvevoltage suppression effectiveness at activated positionVSAvoidexcessive voltage at distant locations
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Voltage control devices are equipped with voltage detection circuits that continuously monitor rail-to-ground voltage at their respective locations. When voltage exceeds predetermined thresholds, the devices activate short circuit switches to equalize potential. The feedback mechanism ensures that voltage control actions are taken only when and where needed, preventing unnecessary voltage fluctuations from spreading to distant locations. Multiple detection points along the train line enable localized feedback control that isolates voltage suppression effects to specific sections.

Inventive Principle:
Principle #23Feedback

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

The system effectively suppresses the generation of excessive rail-to-ground voltages at distant locations, maintaining the voltage within safe limits and reducing the risk of electrical shocks to railway workers.

Implementation Method 1

a rail-to-ground voltage acquisition device that acquires the voltage between the rail and the ground electrode

Methodology Applied
Scientific EffectVoltage detection: Electric Field

Implementation Method 2

a short circuit switch is disposed between a rail and an earth, and a short circuit is caused between the rail and the earth when the rail-to-ground voltage exceeding a predetermined value is detected

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3885183B1Rail-to-ground voltage suppression system
Publication Date: 2025.01.22 HITACHI LTD
  • EP3885183B1 patent drawingFigure 1
  • EP3885183B1 patent drawingFigure 2
  • EP3885183B1 patent drawingFigure 3

AI summary

To suppress a generation of an excessive rail-to-ground voltage at a distant place from a voltage control device due to a spread of a fluctuation of a rail-to-ground voltage at an activated position of the voltage control device to the entire train line. A rail-to-ground voltage suppression system for an electric railway includes a rail-to-ground voltage acquisition device that acquires a rail-to-ground voltage, and a voltage control device that connects a rail and a ground electrode. The voltage control device controls the rail-to-ground voltage at an installation position of the voltage control device by connecting the rail and the ground electrode corresponding to the rail-to-ground voltage acquired by the rail-to-ground voltage acquisition device.