Thermal Trip Assembly Busbar Sensor Insulation
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Solution Overview
Problem
Existing temperature-based trip mechanisms in circuit interrupters, particularly bi-metal based systems, face challenges in precise calibration and performance variability, and the placement of temperature sensors can cause damage or introduce time lags in detecting conductor temperatures.
Innovation Solution
A thermal trip assembly comprising a temperature sensor, an insulating sleeve with high thermal conductivity and low thermal capacitance, and a fastener that couples the sleeve to the busbar, allowing direct contact and accurate temperature sensing, along with an electronic trip unit that outputs a trip signal based on sensed temperature, enhancing calibration and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is placed directly against a conductor to improve temperature sensing accuracy, then measurement precision is improved, but the temperature sensor may be damaged
Solution Approach 1:
The patent introduces an insulating sleeve as an intermediary component between the temperature sensor and the conductor. The sleeve is in direct contact with the conductor and transfers thermal energy to the temperature sensor without requiring the sensor to contact the conductor directly, thus protecting the sensor from damage while maintaining accurate temperature measurement
Solution Approach 2:
The patent replaces the direct mechanical contact between the temperature sensor and conductor with a thermal field-based measurement system. The insulating sleeve conducts heat from the conductor to the sensor, allowing temperature measurement through thermal energy transfer rather than direct physical contact
2Reliability
If a temperature sensor is placed proximate to a conductor to avoid damage, then reliability is improved, but time lag is introduced between sensor readings and actual conductor temperature
Solution Approach 1:
The patent modifies the thermal parameters of the insulating sleeve by selecting materials with high thermal conductivity and low thermal capacitance. This allows the sleeve to rapidly conduct heat from the conductor to the sensor while minimizing the time required for temperature changes to propagate through the sleeve, thereby reducing measurement time lag
Solution Approach 2:
The patent applies different material properties to different parts of the thermal path: the insulating sleeve has high thermal conductivity for rapid heat transfer, while the temperature sensor has low thermal mass for quick response. This localized optimization of thermal properties minimizes overall measurement delay
3Ease of manufacture
If bi-metal based mechanisms are used for temperature-based trips, then ease of manufacture is improved, but manufacturing precision and performance consistency deteriorate due to significant performance variability
Solution Approach 1:
The patent replaces the bi-metal mechanical trip mechanism with an electronic temperature sensing and control system. The electronic system uses a temperature sensor to measure conductor temperature and an electronic trip unit to initiate tripping at a predetermined threshold, eliminating the performance variability inherent in bi-metal mechanisms while maintaining ease of manufacture through standard electronic components
Solution Approach 2:
The patent transitions from a mechanical system with fixed physical properties (bi-metal expansion characteristics) to an electronic system with programmable parameters. The trip threshold can be precisely set and consistently replicated across different devices through electronic configuration, improving manufacturing precision and performance consistency
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 solution provides improved performance and ease of calibration for temperature-based trips, reducing variability and ensuring precise timing for initiating trips, while minimizing sensor damage and lag in temperature detection.
Implementation Method 1
an insulating sleeve with high thermal conductivity and low thermal capacitance
Implementation Method 2
a temperature sensor structured to sense a temperature of the busbar
Data Source
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AI summary
A thermal trip assembly (20) for use with a busbar (60,60') includes a fastener (24), an insulating sleeve (22), a temperature sensor (26) structured to sense a temperature of the busbar, and a thermal trip circuit (30,30') structured to output a trip signal based on the sensed temperature. A portion of the insulating sleeve is disposed between the temperature sensor and the busbar. The fastener couples the insulating sleeve and the temperature sensor to the busbar with the insulating sleeve being in direct contact with a portion of the busbar.