Capacitive AC Power Measurement Without Direct Contact
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Solution Overview
Problem
Existing alternating current power measuring apparatuses face challenges in accurately measuring power supplied to loads without disrupting the power supply, especially when safety measures require turning off the power supply during measurement.
Innovation Solution
The apparatus employs capacitance elements capacitively coupled to conductor wires of electrical cables, with voltage and current measuring parts and a processing unit that computes power by multiplying specified voltage values with effective voltage and current values, allowing power measurement without direct contact and ensuring safety by maintaining capacitance elements in a floating state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct connection to conductor wire is used for measurement, then measurement precision is improved, but safety deteriorates due to risk of electric shock and disruption of power supply
Solution Approach 1:
The patent introduces capacitance elements as intermediary components that couple to the conductor wire through capacitive coupling rather than direct electrical connection. This allows voltage measurement to be obtained while maintaining electrical isolation, thus ensuring safety without sacrificing measurement precision. The capacitance elements act as mediators between the high-voltage conductor and the low-voltage measurement circuit.
2Reliability
If power supply is turned off during measurement, then safety is improved, but productivity deteriorates due to interruption of power supply to load
Solution Approach 1:
The patent enables continuous power supply to the load while simultaneously performing power measurements. The capacitively coupled measurement system operates without interrupting the power flow to the load, achieving both safety and continuous operation. The measurement process does not require shutting down the power supply, thus maintaining productivity.
3Reliability
If capacitance elements are used for non-contact measurement, then safety is improved, but measurement precision deteriorates due to capacitive coupling limitations
Solution Approach 1:
The patent employs parameter changes in the form of using multiple different capacitance values (C1, C2, C3) to measure different phase voltages. By carefully selecting and varying capacitance parameters, the system achieves accurate voltage measurements across all three phases while maintaining safety through capacitive coupling. The processing part uses these capacitance variations to compute precise power measurements.
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 and safe measurement of alternating current power by calculating power values without interrupting the power supply, ensuring precise computation of effective power and power factor, suitable for both single-phase and three-phase alternating current systems.
Implementation Method 1
a first capacitance element (30a) having one end capacitively coupled to a conductor wire (16a) of a first electrical cable (14a)
Data Source
AI summary
An alternating current power measuring apparatus includes a first capacitance element having one end connected to a conductor wire of a first electrical cable of a set of electrical cables for supplying alternating current to a load and having the other end capacitively coupled to a conductor wire of a second electrical cable, a first voltage measuring part which measures a first voltage which is a voltage of both ends of the first capacitance element, a first current measuring part which measures a first current flowing in the first electrical cable, and a processing part which computes a power to be supplied to the load by the set of electrical cables by the multiplication among a proportion between a specified voltage value of a voltage applied to the set of electrical cables and an effective value of the first voltage, the first voltage and the first current.