Rail Signal LED Retrofit Interface Module

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Solution Overview

Problem

The replacement of incandescent lamps with energy-saving LED lamps in rail traffic signal systems is hindered by compatibility issues and the need for complex and costly hardware modifications in signal boxes, particularly in relay interlockings, which are sensitive to current levels and require precise adjustments to maintain safety standards.

Innovation Solution

A device and method that include LED lamps with a power supply interface, an interlocking-side interface, and an interface module with control logic to replicate the voltage and power characteristics of incandescent lamps, using a voltmeter and power absorber to adjust power consumption and simulate the load characteristics of the filament lamp, allowing seamless replacement without modifying the signal box hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If incandescent lamps are replaced with LED lamps to reduce energy consumption, then energy efficiency is improved, but compatibility with existing relay interlockings deteriorates due to different electrical characteristics

Engineering Contradiction:
Improveenergy consumptionVSAvoidcompatibility with relay interlockings
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

An interface module is introduced as an intermediary component between the relay interlocking system and the LED lamp. This module contains control logic that measures the voltage at the interlocking interface and adjusts the power delivered to the LED lamp to reproduce the characteristic curve of the original incandescent bulb, thereby maintaining compatibility with the existing relay interlockings while enabling energy-efficient LED operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The control logic dynamically adjusts electrical parameters (voltage and power) supplied to the LED lamp based on the measured voltage at the interlocking interface. By changing these parameters in real-time, the system reproduces the characteristic curve of the incandescent bulb, ensuring that the relay interlockings receive the expected electrical signals despite the underlying light source being different.

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If LED lamps are used with reduced power consumption, then energy savings are achieved, but the relay interlockings may produce false error reactions due to sensitivity to current levels

Engineering Contradiction:
Improvepower consumptionVSAvoidfalse error reactions in relay interlockings
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The interface module incorporates a voltmeter that continuously measures the voltage present at the interlocking interface and feeds this information back to the control logic. Based on this feedback, the control logic adjusts the power delivered to the LED lamp to maintain the characteristic curve that the relay interlockings expect, thereby preventing false error reactions while still achieving energy savings through optimized LED operation.

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

Enables the replacement of incandescent lamps with LED lamps in a cost-effective and safe manner, ensuring compatibility with existing systems and maintaining the reliability of rail traffic signal systems by accurately replicating the power and voltage characteristics of the original lamps, thus avoiding false error reactions in sensitive relay interlockings.

Implementation Method 1

p) a power absorber (20) which is controlled by the control logic (24) depending on the measured voltage in such a way that the power recorded at the interlocking-side interface reproduces the characteristic curve of the light bulb to be replaced

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP2463174B1Method and device for replacing a bulb of a light signal
Publication Date: 2013.10.30 SIEMENS SCHWEIZ AG
  • EP2463174B1 patent drawingFigure 1~2
  • EP2463174B1 patent drawingFigure 3~4
  • EP2463174B1 patent drawingFigure 5~6

AI summary

The present invention relates to a device for replacing an incandescent lamp (2) with a more energy-efficient light source (12) for a light signal in rail-bound traffic, which is integrated into a signal box-side safety monitoring system, comprising: a) a number of light sources (12), in particular LED lights, with a power supply interface, wherein the number of light sources requires less electrical power than the incandescent lamp (2) to achieve a luminous intensity analogous to that of the incandescent lamp; b) a signal box-side interface (8) for obtaining electrical power from the signal box (4);c) an interface module (IM) connected between the interlocking interface (8) and the power supply interface (10), wherein the interface module (IM) c1) comprises a control logic (24) which knows a signal aspect and/or time-of-day dependent characteristic curve of the incandescent lamp (2) to be replaced and controls the power output to the power supply interface (10) depending on the selected signal aspect and/or the time of day; c2) comprises a voltmeter (30) which measures the voltage applied to the interlocking interface (8) and transmits it to the control logic (24);c3) comprises a power sensor (20) which is controlled by the control logic (24) depending on the measured voltage such that the power consumed at the interlocking interface (8) replicates the characteristic curve of the incandescent lamp (2) to be replaced. In this way, the device makes it possible to integrate an LED light source as a replacement for an incandescent lamp into the light signal in such a way that no notice is received at the interlocking.