Multi-stage Fuse Protection for Electrical Loads
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Solution Overview
Problem
Existing protective devices for electrical energy transmission require downstream components to be dimensioned according to maximum current and voltage limits, leading to increased component sizes and unnecessary nominal ratings, which is inefficient and costly.
Innovation Solution
A protective device with a first overcurrent and overvoltage fuse, along with a second fuse circuit that trips at a lower current intensity, allowing for adaptive protection of electrical loads for different nominal voltages and reducing the need for oversized components by enabling lower current intensity limits downstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single overcurrent protective device with high current intensity limit value is used, then overvoltage protection can be achieved by short-circuiting, but downstream electrical components must be dimensioned for high current and voltage limits, increasing component size and cost
Solution Approach 1:
The protective device is divided into two separate fuse circuits: a first fuse circuit with a higher current intensity limit value for overvoltage protection, and a second fuse circuit with a lower current intensity limit value for normal operation protection. This segmentation allows downstream components to be dimensioned for the lower second limit value while still providing overvoltage protection through the first fuse circuit, thereby reducing component size and cost without sacrificing protection capability
Solution Approach 2:
The invention changes the current intensity limit parameter by introducing two distinct fuse circuits with different limit values. The first fuse circuit operates at a higher current threshold to enable overvoltage protection, while the second fuse circuit operates at a lower threshold to protect downstream components during normal operation. This parameter differentiation resolves the contradiction by allowing components to be designed for the lower parameter while maintaining the higher parameter protection capability
2Reliability
If downstream components are dimensioned for high current and voltage limits to ensure protection, then safety is improved, but component dimensions and nominal currents increase unnecessarily for operation below limit values
Solution Approach 1:
By segmenting the protection function into two fuse circuits with different current intensity limit values, the invention allows downstream components to be dimensioned according to the lower second limit value rather than the higher first limit value. This segmentation enables components to be smaller and lighter while still maintaining protection safety, as the first fuse circuit provides overvoltage protection without requiring downstream components to be oversized
Solution Approach 2:
The invention applies parameter changes by establishing two distinct current intensity limit values. Downstream components are designed for the lower second limit value, reducing their dimensions and weight, while the first fuse circuit with the higher first limit value ensures that overvoltage protection safety is maintained. This parameter differentiation resolves the contradiction between protection safety and component size
Data Source
AI summary
A protective device includes a first fuse circuit, an overvoltage protection circuit, and a second fuse circuit. The first fuse circuit interrupts a flow of a line current from a voltage terminal to the electrical load when an intensity of the line current reaches a first current intensity limit value. The overvoltage protection circuit electrically connects poles of the voltage terminal when a first voltage limit value of a voltage is reached on the first fuse circuit to force the line current to reach the first current intensity limit value. The second fuse circuit activates the overvoltage protection circuit when a second voltage limit value of a voltage on the second fuse circuit is reached to electrically connect the poles of the voltage terminal. The second voltage limit value is based at least in part on a nominal voltage of the electrical load.