Thermal Overload Protection Device with Insulated Sensor
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Solution Overview
Problem
Existing devices for detecting thermal overloads in electrical consumers, such as electric motors, face challenges in monitoring both AC and DC currents, achieving a wide adjustment range, minimizing power loss, and implementing thermal memory with simple galvanic isolation, while current methods like bimetallic releases, current transformers, and shunts have limitations in these areas.
Innovation Solution
A device with a first current path and a monitoring unit comprising a temperature measuring unit, a carrier, and an evaluation unit, where the temperature measuring unit is isolated from the measuring transducer and insulated by additional electrically insulating material, allowing for detection of thermal overloads by analyzing the heating behavior of the measuring transducer over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bimetallic release is used for monitoring, then thermal memory and galvanic isolation can be implemented with little effort, but the device generates high power loss
Solution Approach 1:
The patent introduces a thermal conductor as an intermediary element that transfers heat from the measuring transducer to the bimetallic release. This mediator enables thermal memory functionality while keeping the measuring transducer itself low-power, thus resolving the contradiction between reliability (thermal memory) and energy loss.
2Loss of energy
If a current transformer is used for monitoring, then power dissipation is low and adjustment range is 1 to 10, but no DC currents can be recorded and no thermal memory can be simulated
Solution Approach 1:
The patent combines the advantages of different monitoring methods by integrating a measuring transducer (capable of DC monitoring with low power dissipation) with a bimetallic release (providing thermal memory). The thermal conductor merges these components into a unified system that achieves both DC current monitoring capability and thermal memory functionality while maintaining low power dissipation.
3Adaptability or versatility
If a shunt is used for monitoring, then AC/DC currents can be recorded with setting range 1 to 4, but no thermal memory is simulated and galvanic isolation of individual phases is only possible with great effort
Solution Approach 1:
The thermal conductor acts as a mediator that enables thermal memory functionality without requiring complex galvanic isolation mechanisms. By transferring thermal energy rather than electrical energy, the system achieves phase isolation naturally through the thermal path, simplifying the device structure while maintaining AC/DC monitoring capability.
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 effective detection of thermal overloads in both AC and DC consumers with improved setting range, reduced power loss, and thermal memory, preventing premature activation and ensuring safe cooling, thus protecting the consumer from damage.
Implementation Method 1
The measuring transducer (10) is heated in a defined manner as a function of the current magnitude and the current flow time
Implementation Method 2
a first temperature sensor (11) arranged on a second side surface (152) of the carrier (15) in such a way that it can detect a temperature of the first measuring transducer (10)
Implementation Method 3
an additional electrically insulating material (14) is arranged on a first side surface (151) of the carrier (15) between the first measuring transducer (10) and the carrier (15)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a device (1) for protecting a user (2), the device (1) having a first current path (100) which comprises a first and a second conduit (101, 102), and a monitoring device for detecting an imminent overload of the electric user (2). In order to provide a thermally and electrically optimised, improved and cost-effective device (1) by means of which an imminent overload of a user can be detected, the monitoring device comprises a first temperature measurement unit (18), a support (15), an evaluation unit (4) and a first transducer (10) that produces an electrically conductive connection between the first and second conduits (101, 102) of the first current path (100), the first temperature measurement unit (18) being electrically insulated from the first transducer (10) and comprising a first temperature sensor (11), an additional electrically insulating material (14) being arranged on a first lateral surface (151) of the support (15) between the first transducer (10) and the support (15) and the first temperature sensor (11) being arranged on the support (15) in such a manner that it can detect a temperature of the first transducer (10), the evaluating unit (4) being able to detect an imminent overload at the user (2) on the basis of temperatures detected by the first temperature sensor (11).