Wireless Field Device Protection Circuit for Reverse Polarity and Overvoltage

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Solution Overview

Problem

Low-powered wireless field devices are vulnerable to damage from reverse polarity and overvoltage connections, which can occur when connected to higher voltage power sources, leading to potential component failure.

Innovation Solution

A protection circuit incorporating reverse polarity and overvoltage protection mechanisms using MOSFETs, resistors, and zener diodes to safeguard the device circuitry from such connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If wireless field devices are connected to higher voltage power sources to increase power availability, then power supply capability is improved, but circuitry damage risk increases due to reverse polarity and overvoltage connections

Engineering Contradiction:
Improvepower supply capabilityVSAvoidcircuitry protection
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent introduces a protection circuit as an intermediary component between the power source and the wireless field device circuitry. This protection circuit includes voltage regulation elements and polarity protection mechanisms that mediate the connection, allowing higher voltage power sources to be connected safely while preventing damage from overvoltage and reverse polarity conditions.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection circuit provides beforehand cushioning by preemptively protecting the circuitry from potential damage before it occurs. The circuit includes components that detect and respond to overvoltage and reverse polarity conditions in advance, preventing harmful effects before they can damage the wireless field device components.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If protection circuits are added to prevent reverse polarity and overvoltage damage, then circuitry protection is improved, but device complexity increases

Engineering Contradiction:
Improvecircuitry protectionVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The protection circuit is designed to perform multiple functions simultaneously: overvoltage protection, reverse polarity protection, and voltage regulation. By combining these protection functions into a single integrated circuit module, the patent reduces the overall complexity that would result from separate protection circuits for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges multiple protection functions (overvoltage protection, reverse polarity protection, voltage regulation) into a single integrated protection circuit. This consolidation reduces the number of discrete components and simplifies the overall device architecture while maintaining comprehensive protection capabilities.

Inventive Principle:
Principle #5Merging (Combining)

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 protection circuit effectively prevents damage to low-voltage components by ensuring proper voltage levels and polarity, enhancing device reliability and energy efficiency.

Implementation Method 1

a zener diode having a cathode connected to the drain of the second MOSFET transistor and having an anode connected to ground, wherein the zener diode prevents the voltage between the drain and source of the second MOSFET transistor from exceeding a maximum voltage

Methodology Applied
Scientific EffectZener breakdown: Avalanche Breakdown

Implementation Method 2

A protection circuit incorporating reverse polarity and overvoltage protection mechanisms using MOSFETs, resistors, and zener diodes

Methodology Applied
Scientific EffectField effect: Electric Field

Data Source

PatentEP2774235B1Process control field device with circuitry protection
Publication Date: 2025.07.02 ROSEMOUNT INC
  • EP2774235B1 patent drawingFigure 1
  • EP2774235B1 patent drawingFigure 2
  • EP2774235B1 patent drawingFigure 3

AI summary

A wireless field device (200) for use in an industrial process control system includes a power source (202) having a power source output. Field device is circuitry powered by the power source output. A protection circuit (308) is configured to protect the field device circuitry. The protection circuit (308) includes reverse polarity protection circuit coupled to the power source output that electrically isolates the power source output from the field device circuitry in response to a reverse polarity connection between the power source output and the field device circuitry. An overvoltage protection circuit (310) disconnects the power source output from the field device circuitry is a voltage of the power source output exceeds a threshold.