Galvanically Isolated Aircraft Electronics for Indirect Lightning Protection

Solution Overview

Problem

Current lightning protection measures for electronic devices in aircraft require significant space due to the exponential increase in component area with increasing threat levels, especially for high-impedance interfaces, leading to increased volume and weight, and the risk of failure from indirect lightning strikes.

Innovation Solution

Implementing an electrical device with galvanic isolation of components from the housing and input/output lines using optical, magnetic, capacitive, or mechanical data transmission, and magnetic induction for power supply, eliminating the need for conventional protective elements like gas discharge tubes and resistors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional protective elements (gas discharge tubes, varistors, suppressor diodes, resistors) are used for indirect lightning protection, then lightning protection is achieved, but the device volume and weight increase significantly

Engineering Contradiction:

Improvelightning protectionVSAvoiddevice volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent removes conventional protective elements (gas discharge tubes, varistors, suppressor diodes, resistors) from the device by implementing galvanic isolation through optical, magnetic, capacitive, or mechanical data transmission and magnetic induction for power supply. This extraction eliminates the need for space-consuming protective components while maintaining lightning protection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces conventional electrical protective elements with non-electrical transmission methods. Optical transmission uses light instead of electrical signals, magnetic induction uses magnetic fields instead of direct electrical connections, and capacitive coupling uses electric fields without direct conductive paths. This substitution eliminates the need for protective elements while maintaining protection against lightning-induced current and voltage pulses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conventional protective elements are used for indirect lightning protection, then lightning protection is achieved, but the device weight increases

Engineering Contradiction:

Improvelightning protectionVSAvoiddevice weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent removes conventional protective elements (gas discharge tubes, varistors, suppressor diodes, resistors) from the device by implementing galvanic isolation through optical, magnetic, capacitive, or mechanical data transmission and magnetic induction for power supply. This extraction eliminates the need for space-consuming protective components while maintaining lightning protection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If the number of externally wired interface connections increases, then device functionality increases, but the area required for protective elements increases linearly

Engineering Contradiction:

Improvedevice functionalityVSAvoidprotective element area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent replaces conventional electrical protective elements with non-electrical transmission methods. Optical transmission uses light instead of electrical signals, magnetic induction uses magnetic fields instead of direct electrical connections, and capacitive coupling uses electric fields without direct conductive paths. This substitution eliminates the need for protective elements while maintaining protection against lightning-induced current and voltage pulses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If threat level increases, then lightning protection capability must increase, but component area increases exponentially

Engineering Contradiction:

Improvelightning protection capabilityVSAvoidcomponent area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent removes conventional protective elements (gas discharge tubes, varistors, suppressor diodes, resistors) from the device by implementing galvanic isolation through optical, magnetic, capacitive, or mechanical data transmission and magnetic induction for power supply. This extraction eliminates the need for space-consuming protective components while maintaining lightning protection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces conventional electrical protective elements with non-electrical transmission methods. Optical transmission uses light instead of electrical signals, magnetic induction uses magnetic fields instead of direct electrical connections, and capacitive coupling uses electric fields without direct conductive paths. This substitution eliminates the need for protective elements while maintaining protection against lightning-induced current and voltage pulses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 reduces the device's volume and weight significantly while maintaining high lightning protection, preventing damage from lightning-induced current and voltage pulses, and eliminating the risk of failure from faulty protective elements.

Implementation Method 1

the data transmission between the external and internal data interface parts takes place optically

Methodology Applied

Scientific EffectOptical transmission: Light

Implementation Method 2

the data transmission between the external and internal data interface parts takes place optically, magnetically

Methodology Applied

Scientific EffectMagnetic transmission: Magnetic Field

Implementation Method 3

the data transmission between the external and internal data interface parts takes place optically, magnetically, capacitively

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 4

the electrical energy transfer between the external and internal power supply interface parts takes place by magnetic induction

Methodology Applied

Scientific EffectMagnetic induction: Electromagnetic Induction

Data Source

PatentEP4420244B1Electrical device with indirect lightning protection, attitude and heading reference system, and aircraft

Publication Date: 2025.10.22 NORTHROP GRUMMAN LITEF GMBH

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Figure 2A~2D
Figure 3

AI summary

The invention relates to an electrical device with indirect lightning protection, having an electrically conductive housing, in which electrical components are accommodated. The electrical device further has an electrical data interface, which is connected to the electrical components in order to transmit electrical signals from the components out of the housing, or in order to transmit external electrical signals into the housing in the components. An electrical power supply interface is further provided, which supplies the electronic components with electrical power from an external power source. The electrical data interface and the electrical power supply interface are constructed in such a way that the electrical components are galvanically isolated from the housing and the input/output lines of the data interface and the power supply interface, such that damage to the components by a current pulse brought about by lightning is prevented. An attitude and heading reference system and an aircraft comprising the electrical device are further provided.