Overcurrent Protection Device Estimating Wire Thermal Characteristic
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Solution Overview
Problem
Conventional overcurrent protection devices rely on fixed thermal characteristics, which do not account for variations in electric wire types and diameters, leading to inadequate protection across different load circuits, particularly in applications with multiple electric loads and wire types.
Innovation Solution
An overcurrent protection device with a switching element, current detector, characteristic estimation portion, and controller that estimates the thermal characteristics of the electric wire based on detected load current and ambient conditions, allowing for adaptive overcurrent protection across various load circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined fixed value is used as the thermal characteristic of the electric wire, then the device structure is simple, but the protection accuracy deteriorates because thermal characteristics vary with wire type and diameter
Solution Approach 1:
The patent applies the dynamics principle by transitioning from fixed thermal characteristic values to dynamically estimated values. The estimation portion continuously determines thermal characteristics based on actual operating conditions including measured temperature and current values, allowing the protection device to adapt to varying wire types and diameters without requiring manual configuration or multiple devices.
Solution Approach 2:
The patent implements self-service by enabling the overcurrent protection device to automatically estimate its own thermal characteristics through the estimation portion. The device uses its own measured temperature and current data to determine appropriate thermal characteristics, eliminating the need for external configuration or pre-programming for different wire types.
2Reliability
If multiple overcurrent protection devices are prepared for various load circuits with different wire types, then the protection accuracy for each circuit is improved, but the device complexity and quantity increase
Solution Approach 1:
The patent applies universality by designing a single overcurrent protection device that can serve multiple different load circuits with various wire types and diameters. The estimation portion enables the device to automatically adapt its thermal characteristics to match the specific wire being protected, making one device replace multiple specialized devices while maintaining protection accuracy for each circuit type.
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 overcurrent protection by dynamically determining the thermal characteristics of the electric wire, ensuring appropriate operation without the need for multiple protection devices, thus providing a general-purpose solution adaptable to various load circuits.
Implementation Method 1
The current detector detects the load current
Implementation Method 2
the thermal characteristic of the electric wire may differ according to the wire type and the wire diameter of the electric wire
Data Source
AI summary
An overcurrent protection device is to be provided between a power supply and a load circuit including an electric load and an electric wire electrically connected with each other, and includes a switching element, a current detector, a characteristic estimation portion, and a controller. The switching element switches flowing and interrupting of a load current that flows from the power supply to the electric load. The current detector detects the load current. The characteristic estimation portion estimates a thermal characteristic of the electric wire based on the load current detected by the current detector. The controller outputs an overcurrent protection signal for interrupting the load current so as to protect the load circuit from an overcurrent to the switching element based on the thermal characteristic estimated by the characteristic estimation portion and the load current detected by the current detector.