Utility Meter Surge Protection Module With MOV Fuse Isolation

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Solution Overview

Problem

Utility meters are vulnerable to high voltage surge events and abnormal overload conditions, which can lead to catastrophic failure, resulting in increased replacement costs and downtime due to the limitations of existing protection mechanisms like metal-oxide varistors (MOVs) and the risk of chemical ejection causing damage to surrounding components.

Innovation Solution

A high-voltage protection module is introduced, featuring a metal-oxide varistor (MOV) coupled with a series limiting resistor and a fuse, which allows the fuse to break currents during overvoltage events, and a housing design that vents chemical ejections away from sensitive components, preventing catastrophic failure and maintaining communication functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal-oxide varistors (MOVs) are used for protection, then protection capability is improved, but risk of chemical ejection causing damage to surrounding components increases

Engineering Contradiction:

Improveprotection capabilityVSAvoidchemical ejection

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the MOV component from the system by designing a protection module that opens the circuit before the MOV can fail and eject chemicals. The fuse and series limiting resistor work together to prevent MOV failure, thereby eliminating the harmful chemical ejection effect while maintaining protection capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of MOV failure into a beneficial protective mechanism by using the series limiting resistor and fuse to control the circuit current. This prevents the MOV from reaching failure conditions, transforming what would be a harmful event into a controlled protective function.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If existing protection mechanisms are used, then some protection is provided, but catastrophic failure can still occur leading to increased replacement costs

Engineering Contradiction:

Improveprotection levelVSAvoidreplacement costs

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements beforehand cushioning by placing a fuse and series limiting resistor in the circuit path before the protected components. These elements are designed to fail safely first, absorbing the energy of surge events and preventing catastrophic failure of the main meter components, thereby avoiding expensive replacements.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent segments the protection function into multiple independent components: a fuse for overcurrent protection, a series limiting resistor for current limitation, and an MOV for voltage clamping. This segmentation allows each component to handle specific aspects of surge protection, preventing total system failure and reducing replacement costs.

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If utility meters are installed outside buildings, then accessibility is improved, but vulnerability to high voltage surges increases

Engineering Contradiction:

ImproveaccessibilityVSAvoidhigh voltage surge

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent introduces intermediary protective components (fuse, series limiting resistor, and MOV) between the utility meter and the power grid. These intermediaries act as mediators that absorb and divert high voltage surges before they can reach the meter, allowing the meter to be installed in vulnerable outdoor locations without increasing risk.

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 solution enables utility meters to fail gracefully under high voltage and overload conditions, preventing damage to the meter and surrounding structures while ensuring continuous communication and reducing replacement costs.

Implementation Method 1

a metal-oxide varistor (MOV) coupled across a mains power line

Methodology Applied

Scientific EffectVaristor effect:

Implementation Method 2

a resistor electrically coupled to the MOV in series and in front of the MOV

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

a fuse electrically coupled to the MOV and the resistor in series, the fuse opens upon an overvoltage event disengaging alternating current (AC) power from the mains power line to the metrology device

Methodology Applied

Scientific EffectFusing:

Data Source

PatentUS12155196B2Metrology device including a high-voltage protection module

Publication Date: 2024.11.26 ITRON INC

AI summary

A high-voltage protection module for a metrology device includes a metal-oxide varistor (MOV) coupled across a mains power line, a resistor electrically coupled to the MOV in series with the MOV, and a fuse electrically coupled to the MOV and the resistor in series, the resistor being located between the fuse and the MOV. The fuse opens upon an overvoltage event disengaging alternating current (AC) power from the mains power line to the metrology device.