Short-Circuit Resistor with Parallel Coils for Adjustable Ohmic Value
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Solution Overview
Problem
Existing current limiting resistors in circuit breakers face issues with high temperature resistance requirements, material costs, and lack of modularity in ohmic value adjustment, leading to inefficient and costly designs.
Innovation Solution
A multi-wire current limiting resistor with flat coils held by side plates, where the ohmic value can be varied by connecting multiple coils in parallel, using stainless steel wire with enamel insulation, and a winding method that cancels magnetic fields to reduce temperature and allow for standard, inexpensive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-wire resistor with thick wire or strip is used, then the resistor can withstand high temperatures (up to 800°C), but the material cost increases and the ohmic value cannot be easily adjusted
Solution Approach 1:
The resistor is divided into multiple parallel wire segments (at least two wires) instead of using a single thick wire or strip. Each wire has its own insulation layer, and they are arranged in parallel to achieve the desired total ohmic value. This segmentation allows for easy adjustment of the ohmic value by changing the number, length, or cross-sectional area of individual wires, while each wire operates at a lower temperature due to distributed current load.
2Device complexity
If a single-wire resistor configuration is used, then the structure is simple, but the ohmic value cannot be varied without modifying the entire winding
Solution Approach 1:
The resistor structure is segmented into multiple independent wire elements that can be individually adjusted. Each wire maintains its own insulation and can be independently modified in length, cross-sectional area, or material composition. This allows the total ohmic value to be varied by changing only specific wire parameters rather than redesigning the entire resistor structure, thus maintaining relative simplicity while achieving high adaptability.
Solution Approach 2:
The resistor design incorporates adjustable parameters (number of wires, their lengths, cross-sectional areas) that can be dynamically modified to achieve different ohmic values. This dynamic configurability allows the same basic structure to serve multiple circuit breaker ratings and locations in the electrical distribution tree, providing versatility without increasing structural complexity.
3Temperature
If high-temperature resistant materials (such as ceramic support and nichrome wire) are used, then the resistor can withstand temperatures up to 800°C, but the material cost increases significantly
Solution Approach 1:
The patent changes the operating temperature parameter by using multiple parallel wires with adequate insulation, which distributes the heat generation and keeps each wire's temperature below 150°C during normal operation and even during short circuits. This parameter change allows the use of inexpensive standard materials like enameled copper or aluminum wires instead of expensive high-temperature materials like ceramic supports and nichrome wire, significantly reducing material costs while maintaining safety.
4Temperature
If adequate insulation is provided for high-temperature operation, then the resistor can withstand thermal stress, but the insulation requirements become more stringent and costly
Solution Approach 1:
By changing the temperature parameter through multiple parallel wire configuration, the patent reduces the operating temperature to below 150°C, which allows the use of standard insulation materials and manufacturing processes. The insulation requirements become常规 (standard) rather than stringent, making the resistor easier to manufacture with commonly available materials and techniques, while still providing adequate thermal stress resistance for the reduced temperature regime.
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 effectively limits temperature below 150°C, allows for adjustable ohmic values, and enables the use of standard materials, improving safety and cost-effectiveness while maintaining compactness and efficient manufacturing.
Implementation Method 1
each coil consisting of a wire provided with electrical insulation means
Implementation Method 2
the temperature of the resistor material does not rise above 150° C
Data Source
Figure 1~2
Figure 3~4c
AI summary
The apparatus has a main current circuit, and an auxiliary circuit in which current passes when the main circuit is cut-off after occurrence of a short-circuit. The auxiliary circuit comprises a current limiting resistor including flat coils (5) maintained by side flanges (1, 3) made of thermoplastic material. The resistor includes a variation unit for varying ohmic value of the resistor by association of the coils in parallel. Each coil includes a wire equipped with an electric insulation unit, where the wire is made of stainless steel. Independent claims are also included for the following: (1) a method for winding a magnetically neutral coil (2) a method for forming electric connections of a resistor.