Measuring Apparatus Leakage Current Control via Parallel Switch
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Solution Overview
Problem
The existing measuring apparatus experiences leakage currents when measuring high voltages, potentially tripping earth leakage breakers, and takes a long time to interpose a protective resistor during resistance measurement range switching, leading to risks of large leakage currents.
Innovation Solution
A measuring apparatus with a protective resistor and a switch connected in parallel to the current supplier, allowing the processor to control the switch state based on voltage levels to minimize leakage currents and quickly interpose the resistor during resistance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the current supplier is constantly connected to the input terminal with low output resistance, then resistance measurement can be performed continuously, but leakage current increases when measuring high voltage
Solution Approach 1:
The patent applies dynamics by making the connection state of the current supplier changeable rather than fixed. A switch is introduced to dynamically control the connection between the current supplier and the input terminal, allowing the system to transition between connected and disconnected states based on measurement requirements, thereby resolving the contradiction between continuous measurement capability and leakage current reduction.
Solution Approach 2:
The patent introduces a switch as an intermediary component between the current supplier and the input terminal. This mediator controls the flow of measurement current, enabling the system to disconnect the current supplier when high voltage is detected, thus preventing leakage current while maintaining the capability for continuous resistance measurement when needed.
2Object-generated harmful factors
If a protective resistor is interposed between the input terminal and current supplier during resistance measurement range switching, then leakage current is reduced, but the switching time increases
Solution Approach 1:
The patent applies preliminary action by detecting the voltage level before the resistance measurement range switching is completed and proactively controlling the switch to disconnect the current supplier. This anticipatory control prevents leakage current from occurring in the first place, rather than waiting for the protective resistor to be interposed after the fact, thereby reducing the time loss associated with range switching.
3Reliability
If the switch is kept in the open state to prevent leakage current, then safety is improved, but resistance measurement cannot be performed
Solution Approach 1:
The patent resolves this contradiction through dynamic control of the switch state. The switch is not permanently open or closed but changes state based on real-time voltage detection and measurement mode requirements. During voltage measurement or high voltage conditions, the switch remains open for safety. During resistance measurement with low voltage, the switch closes to enable measurement, thus maintaining both safety and measurement capability.
Solution Approach 2:
The patent applies parameter changes by monitoring voltage level as a key parameter and using it to control the switch state. When the detected voltage exceeds a threshold, the switch opens to prevent leakage current. When voltage is within safe limits and resistance measurement is required, the switch closes to enable current flow. This parameter-based control allows the system to adapt between safety and measurement functionality.
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 significantly reduces leakage current values, preventing earth leakage breaker tripping and ensuring the protective resistor is interposed swiftly, even when switching between resistance measurement ranges.
Implementation Method 1
a protective resistor being interposed on a current supply line Li between one input terminal 2, 3 and an output terminal of the current supplier 9
Data Source
AI summary
The present invention aims to reduce the leakage current that flows when measuring a high voltage and includes: a voltage detector that detects a voltage and outputs a detection voltage; a current supplier that supplies a measurement current across a pair of input terminals via a protective resistor; and a processor that executes a voltage measurement process, which measures the voltage based on data indicating the detection voltage, and a resistance measurement process, which measures a resistance connected between the input terminals based on the voltage and the current. A first switch is connected in parallel to the protective resistor and the processor executes the voltage measurement process in a state where the first switch has been set open to measure the terminal voltage, and executes the resistance measurement process by setting the first switch shorted when the voltage is equal to or below the reference voltage value.