Electricity Meter Relay State Detection via Control Current
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Solution Overview
Problem
Existing electricity meters with auxiliary cut-off devices, which use electromechanical relays, face issues with detecting relay malfunctions without increasing the meter's size or cost, as conventional methods require transmitting information through galvanic isolation or rely on expensive vibration-detecting accelerometers.
Innovation Solution
An electricity meter with a control circuit and measurement circuit that generates commands to open or close the electromechanical relay, measuring the control current to detect the actual state of the relay without transmitting through galvanic isolation, using a simple and compact measurement circuit to determine the real open or closed state and detect faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If information about the actual state of the auxiliary switching device is transmitted through galvanic isolation, then the reliability of state detection is improved, but the cost and size of the meter increase due to additional isolation and measurement components
Solution Approach 1:
The patent introduces a magnetic coupling intermediary between the control circuit and measurement circuit. The control current generates a magnetic field that couples through a magnetic component to the measurement circuit, enabling state detection without direct galvanic isolation. This intermediary approach maintains detection reliability while eliminating bulky isolation components.
Solution Approach 2:
The patent replaces the mechanical/electrical galvanic isolation system with a magnetic field-based detection system. Instead of using physically isolated measurement components that require direct electrical contact across isolation barriers, the invention uses magnetic coupling to transmit state information, thereby reducing component complexity while maintaining reliability.
2Reliability
If an accelerometer is used to detect relay switching vibrations, then the reliability of malfunction detection is improved, but the cost and mass of the meter increase
Solution Approach 1:
The patent replaces the mechanical accelerometer-based vibration detection system with an electrical measurement system. Instead of using a physical accelerometer to detect mechanical vibrations from relay switching, the invention measures the electrical control current characteristics, which vary depending on whether the relay is functioning properly. This substitution eliminates the need for heavy accelerometer components while maintaining detection reliability.
Solution Approach 2:
The patent creates an electrical copy of the mechanical switching event. Rather than directly measuring the mechanical vibration of the relay contacts, the system measures the corresponding electrical phenomenon (control current variation) that occurs during switching. This electrical copy provides the same diagnostic information without requiring mechanical sensing components.
3Measurement precision
If a complex measurement circuit with galvanic isolation is used, then the measurement precision of the relay state is improved, but the volume of the meter increases
Solution Approach 1:
The patent uses magnetic coupling as an intermediary to achieve precise measurement without bulky isolation components. The magnetic field serves as a compact mediator that transfers state information from the control circuit to the measurement circuit, maintaining measurement precision while occupying minimal space compared to traditional galvanic isolation components.
Solution Approach 2:
The patent changes the measurement parameter from direct voltage/current measurement across isolation barriers to magnetic field-based current measurement. By measuring the control current characteristics that change during relay switching, the system achieves precise state detection using a compact measurement circuit without requiring large isolation components.
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
Enables reliable and cost-effective detection of electromechanical relay malfunctions without increasing the meter's volume or mass, ensuring accurate switching operations and reducing additional costs associated with insulation and measurement components.
Implementation Method 1
an electromechanical relay equipped with at least one control coil (2, 3)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Electric meter intended to measure electrical energy supplied to an installation by an electrical network, the electric meter comprising a switching device arranged to selectively connect equipment of the installation to the electrical network, the switching device comprising an electromechanical relay (1) equipped with at least one control coil (2, 3), the electric meter further comprising a control circuit (5) arranged to generate an opening or closing command of the electromechanical relay, the opening or closing command producing a control current (Ico, Icf) circulating in the control coil, the electric meter further comprising a measuring circuit (18) arranged to produce measurements of the control current, and to detect an actual open or closed state of the electromechanical relay from the measurements of the control current.