Electricity Meter Switching Delay Estimation via Resonant Inductive Circuit
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Solution Overview
Problem
Modern electrical energy meters face challenges in accurately opening and closing a cut-off device to prevent electric arcs and extend its service life, especially when dealing with sinusoidal alternating currents, which is complex and costly due to parasitic signals and requires dedicated switching devices.
Innovation Solution
An electric meter with a resonant inductive circuit, transmission means for voltage pulses, and detection means to estimate delays between command and effective action, allowing precise timing of cut-off device operations without increasing costs by using a pre-existing switching device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct current and voltage measurements are used to time the opening and closing of the cut-off device, then precise timing is achieved, but the device complexity increases due to parasitic signals disturbing measurements
Solution Approach 1:
The patent introduces an intermediary mechanical detection system using a light barrier and optical sensor to detect the position of the movable contact. This intermediary mechanism translates the mechanical state of the switch into an electrical signal, avoiding direct measurement of current and voltage during switching when parasitic signals occur. The optical detection system serves as a mediator that provides clean, disturbance-free timing signals for controlling the cut-off device operations.
2Measurement precision
If a dedicated switching device with light barrier detection is designed to detect effective opening and closing, then measurement accuracy is improved, but the manufacturing cost increases
Solution Approach 1:
The patent makes the switching device universal by integrating multiple functions into a single component: the movable contact serves both as the electrical conductor for current flow and as the target for optical detection. The same mechanical structure performs both electrical switching and position sensing functions, eliminating the need for separate dedicated detection hardware. This multi-functionality reduces component count and manufacturing complexity while maintaining detection accuracy.
3Ease of operation
If the cut-off device is opened when current amplitude is high, then operational simplicity is maintained, but electric arcs form weakening the device and reducing service life
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual position of the movable contact through the optical detection system and using this information to determine the precise timing for opening and closing operations. The system measures the actual switching moment and uses this feedback to anticipate and adjust the timing of subsequent operations, ensuring they occur at optimal moments when current or voltage is near zero. This feedback mechanism maintains operational simplicity while dramatically improving reliability by preventing high-current arcing.
Solution Approach 2:
The patent applies preliminary action by measuring the opening and closing delays in advance and using these pre-determined values to anticipate the optimal timing for subsequent operations. The system calculates the delay between command issuance and actual switching based on previous measurements, then uses this information to time future operations proactively. This preliminary characterization of switching behavior enables the system to consistently achieve zero-current or zero-voltage switching without complex real-time calculations, maintaining operational simplicity while ensuring device reliability.
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 accurate opening and closing of the cut-off device when current or voltage is zero, reducing electric arc formation and extending device life without the need for dedicated hardware, thus maintaining meter functionality and reducing costs.
Implementation Method 1
a resonant inductive circuit comprising a coil mounted fixed relative to the switching device opposite a path of a moving contact of the switching device
Implementation Method 2
an inductive circuit (6) comprising a coil (10)
Data Source
Figure 1~5
AI summary
Electric meter comprising means for estimating the opening and closing time of a switching device (3), the estimation means comprising: - a resonant inductive circuit (6) including a coil (10) mounted opposite a movable contact (5) of the switching device; - transmission means arranged to emit a voltage pulse into the inductive circuit; - detection means arranged to detect a damped oscillatory signal (So) at the output of the inductive circuit, and to detect the position of the movable contact (5) and therefore the actual opening or closing of the switching device as a function of the number of oscillations; - measurement means for measuring the time between the opening command and the detection of the actual opening, and between the closing command and the detection of the actual closing.