Fuse Frequency Separation Lightning Surge Protection

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Solution Overview

Problem

Conventional fuses can melt and break due to lightning surge currents, rendering devices inoperable, and increasing the melting current value to prevent this also compromises their ability to block abnormal currents.

Innovation Solution

A fuse with a frequency separation function that includes distinct paths for normal, abnormal, and lightning surge currents, utilizing a high frequency transmitting portion and an abnormal current melting portion to separate and block currents effectively, with the melting mechanism only engaging with abnormal currents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fuse is used to protect against abnormal currents, then abnormal currents can be blocked, but the fuse may also melt and break due to lightning surge currents, rendering devices inoperable

Engineering Contradiction:

Improveability to block abnormal currentVSAvoiddamage from lightning surge current

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The fuse structure segments the current paths so that lightning surge currents and abnormal currents are handled separately. The first transmitting portion is designed with high current tolerance for lightning protection, while the second transmitting portion maintains standard fuse characteristics for abnormal current blocking, preventing false operation during lightning events.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The impedance characteristics of the transmitting portions are changed based on frequency parameters. The first transmitting portion has inductance L1 and capacitance C1 tuned to present low impedance to high frequency lightning surge currents, while the second transmitting portion presents appropriate impedance to low frequency abnormal currents, enabling selective current routing based on frequency parameters.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a fuse melts and breaks to block abnormal current, then abnormal current entry is blocked, but the device including the fuse can no longer be functional

Engineering Contradiction:

Improveability to block abnormal currentVSAvoiddevice operational continuity

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The fuse is segmented into two independent transmitting portions, each handling different current types. The first transmitting portion protects against lightning surge currents without affecting device operation, while the second transmitting portion blocks abnormal currents when necessary. This segmentation allows the fuse to provide comprehensive protection while maintaining device functionality during lightning events.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The frequency separation function acts as an intermediary that directs lightning surge currents away from the melting mechanism portion through the first transmitting portion. This prevents unnecessary melting and device shutdown during lightning events, while still allowing the melting mechanism to operate appropriately for abnormal currents that pass through the second transmitting portion.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 fuse maintains functionality during lightning surge events by not melting or breaking with lightning surge currents while effectively blocking abnormal currents by melting and breaking with abnormal current flow.

Implementation Method 1

a first transmitting portion provided between the input port portion and the output port portion, the first transmitting portion configured to transmit the lightning surge current that enters the input port portion and guide the lightning surge current to the output port portion

Methodology Applied

Scientific EffectSkin effect: Skin Effect

Implementation Method 2

a melting mechanism portion provided between the input port portion and the second transmitting portion or between the second transmitting portion and the output port portion, the melting mechanism portion configured to melt and break when the normal current passes, and configured to melt and break when the abnormal current passes

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11410827B2Fuse having frequency separation function

Publication Date: 2022.08.09 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

A fuse with a frequency separation function includes an input port portion, an output port portion, a first transmitting portion between the input port portion and the output port portion, the first transmitting portion configured to transmit a lightning surge current entering the input port portion and guide the lightning surge current to the output port portion, a second transmitting portion between the input port portion and the output port portion, the second transmitting portion configured to be capable of transmitting a normal current and an abnormal current entering the input port portion, and a melting mechanism portion which is provided between the second transmitting portion and the input port portion or between the second transmitting portion and the output port portion, the melting mechanism configured not to melt and break when the normal current passes, and configured to melt and break when the abnormal current passes.