Antenna Isolation Board for Smart Meter Retrofit Safety

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Solution Overview

Problem

Smart electricity meters often require external antennas for reliable communication, but existing solutions fail to provide a cost-effective and safe method for retrofitting external antennas in meters already connected to grid voltage, posing a risk of electrical shock and increasing installation costs.

Innovation Solution

The design includes a slot in the meter housing for retrofitting an antenna isolation board, which connects to the main board without exposing installers to grid voltage, using a galvanic isolation circuit with two plate capacitors on a multilayer PCB to ensure safety and reduce costs by only isolating meters that need external antennas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If external antenna connection is implemented in all meters, then communication reliability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The antenna isolation board is designed as a separate, removable module that can be independently installed only in meters requiring external antenna connections. This segmentation allows the isolation circuitry to be added selectively rather than universally, reducing overall manufacturing costs while maintaining communication reliability where needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Galvanic isolation is implemented only in the specific location where external antenna connections are made (the antenna isolation board), rather than throughout the entire meter. This localized approach provides the necessary safety and reliability improvements at the point of external connection without unnecessarily increasing manufacturing costs across the entire device.

Inventive Principle:
Principle #3Local quality

2Object-affected harmful factors

If galvanic isolation is implemented for external antennas, then user safety is improved, but device complexity increases

Engineering Contradiction:
Improveuser safetyVSAvoiddevice complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The galvanic isolation circuit is segmented into a separate antenna isolation board module, containing the necessary capacitors and isolation components. This modular approach provides the required user safety through galvanic isolation while minimizing overall device complexity by confining the complex isolation circuitry to a dedicated, self-contained module rather than distributing it throughout the entire meter.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The antenna isolation board acts as an intermediary component between the external antenna and the meter's internal circuits. It provides galvanic isolation through its capacitor-based circuitry, safely mediating the connection between the external antenna and the radio circuit while protecting users from high voltage exposure.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If antenna isolation board is integrated into main board, then device complexity is reduced, but adaptability for retrofitting decreases

Engineering Contradiction:
Improvedevice complexityVSAvoidretrofitting capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The antenna isolation board is designed as a separate, removable module with its own connector and mounting structure, rather than being permanently integrated into the main board. This segmentation enables retrofitting of external antenna capability in already-installed meters while keeping the isolation circuitry as a distinct, adaptable component.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The antenna isolation board is designed with dynamic installability - it can be easily inserted and removed from the meter housing through a dedicated slot. This dynamic characteristic allows the isolation board to be added or removed as needed, providing adaptability for retrofitting while maintaining relatively simple device architecture.

Inventive Principle:
Principle #15Dynamics

4Reliability

If external antenna connection is added to installed meters, then communication reliability is improved, but installation risk increases

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidinstallation risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The antenna isolation board is designed as a pre-assembled module containing the galvanic isolation circuitry, antenna connector, and mounting structure. This segmentation allows the entire isolation assembly to be installed as a single unit through a dedicated slot, improving communication reliability while minimizing installation risk by eliminating the need for installers to work with exposed high-voltage circuits.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The antenna isolation board serves as an intermediary safety barrier that can be installed without exposing installers to high voltage. The galvanic isolation circuitry within the board creates an electrical barrier that protects users during installation and operation, enabling safe retrofitting of external antenna capability in already-installed meters.

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

This solution allows for safe and cost-effective retrofitting of external antennas in smart electricity meters, reducing the need for galvanic isolation in most meters and protecting users from grid voltage while lowering installation costs by enabling easy and tool-free installation of the antenna isolation board.

Implementation Method 1

an isolation circuit providing an antenna signal path and a galvanic isolation barrier between the main board connector and the antenna connector

Methodology Applied
Scientific EffectGalvanic isolation: Capacitance

Implementation Method 2

using a galvanic isolation circuit with two plate capacitors on a multilayer PCB

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP3650870B1Electricity meter with antenna isolation board
Publication Date: 2021.09.22 KAMSTRUP
  • EP3650870B1 patent drawingFigure 1~2b
  • EP3650870B1 patent drawingFigure 3a~4
  • EP3650870B1 patent drawingFigure 5~6c

AI summary

An electricity meter adapted for retrofitting of an external antenna and associated antenna isolation. The electricity meter includes measurement circuit and a radio circuit which are subject to grid voltage, a connector for connecting the external antenna is also subject to grid voltage. The meter housing is arranged to enclose the measurement circuit and the radio circuit to prevent electrical chock. The meter housing comprises a slot through which an antenna isolation board is connected to the main board. The antenna isolation board comprises connectors for engaging the radio circuit and an antenna cable. Further the antenna isolation board provides an isolation circuit providing an antenna signal path and a galvanic isolation barrier between the connectors. The connector on the antenna isolation board is arranged to engage with the connector for connecting an external antenna, when the antenna isolation board is inserted into the slot.