Switchgear Temperature Measurement Using Insulating Thermal Mediator

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Solution Overview

Problem

Existing temperature measurement methods for medium and high voltage switchgear are hindered by the inability to maintain insulation resistance at live components, making contact-based measurements impossible, and non-contact infrared methods are often inaccessible due to power connection configurations, while wireless sensors are difficult to install.

Innovation Solution

A temperature measurement system for switchgear that includes a heat-conductive temperature measuring head connected to an electrically insulating temperature transmission element with different thermal expansion coefficients, which transmits temperature data through a medium to a conversion element generating a signal displayed or stored by a signaller, capable of wireless communication and cloud-based processing for monitoring and alerting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contact-based temperature measurement is used, then measurement precision is improved, but insulation resistance cannot be maintained due to high voltages exceeding 1000V

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidinsulation resistance
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

A thermally conductive but electrically insulating intermediate element (such as a thermally conductive plastic or ceramic rod) is introduced between the high-voltage connection point and the temperature sensor. This intermediary transfers heat from the hot spot to the sensor while blocking electrical current, enabling contact-based temperature measurement without compromising insulation resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct electrical contact measurement with a thermally conductive mechanical connection. Instead of using an electrical sensor that would conduct current, a mechanically connected thermal pathway (through thermally conductive insulating material) is used to transmit temperature information without electrical conductivity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If non-contact infrared temperature measurement is used, then insulation resistance is maintained, but power connections are not always visually accessible making measurement infeasible

Engineering Contradiction:
Improveinsulation resistanceVSAvoidvisual accessibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

A thermally conductive insulating rod or extension element acts as a mediator that extends the sensing capability to inaccessible locations. The rod can be inserted into or positioned near the power connection, transferring thermal energy from hard-to-reach hot spots to the sensor location where measurement is feasible, while maintaining electrical insulation throughout the transmission path.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If wireless temperature sensors are used, then insulation resistance is maintained and measurement is possible, but sensors are difficult to position and very time-consuming to replace

Engineering Contradiction:
Improveinsulation resistanceVSAvoidinstallation and replacement time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The temperature measurement system is segmented into a fixed mounting structure and a removable sensor component. The sensor can be quickly detached and reattached without complex positioning procedures, significantly reducing replacement time while maintaining reliable thermal and electrical connections through the segmented design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mounting structure and connection interfaces are pre-configured during installation to enable rapid sensor replacement. Alignment features, pre-positioned thermal pathways, and plug-and-play electrical connections are established in advance, allowing sensors to be swapped quickly without time-consuming positioning or calibration procedures.

Inventive Principle:
Principle #10Preliminary action

4Measurement precision

If wired temperature sensors are used, then measurement precision is improved, but voltages exceeding 1000V prevent maintenance due to insulation requirements

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidmaintenance capability
Core Design Contradiction:
Measurement precisionVSEase of repair

Solution Approach 1:

A removable thermally conductive insulating element serves as an intermediary that can be safely handled and replaced by maintenance personnel. This intermediary maintains the thermal connection to the high-voltage component while providing electrical isolation, allowing the sensor itself to be replaced without exposing personnel to dangerous voltages.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The temperature sensor is extracted from the high-voltage environment and placed in a separate, accessible location connected through a thermal pathway. The sensor can be removed and replaced without being physically attached to live components, extracting the maintenance burden from the high-voltage zone while preserving measurement capability through the thermal connection.

Inventive Principle:
Principle #2Taking out (Extraction)

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 reliable, cost-effective, and easy-to-install temperature measurement and monitoring of switchgear, allowing for timely maintenance and operational state assessment with threshold-based warnings and control signals.

Implementation Method 1

the temperature sensor is designed to be thermally conductive such that it assumes or approximates a first temperature of the first electrical connection or the second electrical connection, and the temperature sensor is designed to transfer the first temperature to the temperature transfer medium arranged in the temperature transfer element

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the temperature transfer element and the temperature transfer medium have different coefficients of thermal expansion. The characteristic volume of the temperature transfer medium acts on the temperature conversion element

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3811044B1Switching system temperature measurement
Publication Date: 2023.03.22 SIEMENS AG
  • EP3811044B1 patent drawingFigure 1~2
  • EP3811044B1 patent drawingFigure 3
  • EP3811044B1 patent drawingFigure 4

AI summary

The invention relates to a switching system, comprising a switch for medium voltages and/or high voltages, wherein the switch has a first electrical connection on a first side of the switch, and a second electrical connection on a second side of the switch. A medium voltage or high voltage is supplied to the switch via the first electrical connection, and a medium voltage or high voltage is conducted away from the switch via the second electrical connection, or vice versa, and a temperature measuring unit, wherein the temperature measuring unit has a temperature measuring head, a temperature transmission element, a temperature transmission medium, a temperature conversion element, and a temperature signaling device.