Earth State Detection Circuit for High-Voltage DC Apparatus
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Solution Overview
Problem
High-voltage electrical apparatuses, such as those using glass tube high-voltage excitation laser generators, face challenges in detecting earth leakage due to the change from AC to DC power supply, making it difficult for traditional Earth Leakage Circuit Breakers to effectively prevent leakage.
Innovation Solution
An earth detection circuit is developed that includes first and second detection units to determine the earth state by detecting power between the power supply line, neutral line, and earth line, allowing for simultaneous detection of normal and reversed-phase connections, and determining if the earth line is earthed or not.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Earth Leakage Circuit Breaker (ELB) is used for high-voltage electrical apparatus with DC power supply, then leakage prevention is intended, but the ELB cannot effectively detect leakage due to DC power supply characteristics
Solution Approach 1:
The invention changes the detection parameter from AC-specific zero-sequence current (used by traditional ELB) to voltage-based detection that works with DC power supply. The detection unit measures voltage between the earth line and power supply/neutral lines to determine earth leakage, adapting the detection mechanism to DC characteristics.
Solution Approach 2:
The invention replaces the traditional electromagnetic-based ELB mechanism with an electronic detection system using detection units, rectifier circuits, and control circuits. This substitution enables leakage detection in DC systems where traditional electromagnetic ELBs fail.
2Reliability
If voltage detection method (Patent Document 1-4) is used to determine earth state, then earth detection is achieved, but phase connection status (normal or reversed phase) cannot be determined
Solution Approach 1:
The invention makes the detection unit perform multiple functions: it not only detects earth leakage by measuring voltage between earth line and power lines, but also determines phase connection status (normal or reversed phase) by analyzing the same voltage measurements. This multi-functionality eliminates the need for separate detection systems.
Solution Approach 2:
The invention combines earth detection and phase detection functions into a single integrated detection system. The detection unit simultaneously provides information about both earth connection status and phase configuration by processing voltage measurements in a unified manner.
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 enables effective detection of earthing and phase connection status, ensuring safety by preventing leakage and accurately determining if the earth line is connected, regardless of the power supply phase.
Implementation Method 1
a first detection unit for detecting whether there is power between a power supply line L of a commercial power supply and an earth line G of the commercial power supply
Implementation Method 2
a second detection unit for detecting whether there is power between a neutral line N of the commercial power supply and the earth line G of the commercial power supply
Data Source
AI summary
A method capable of effectively detecting an earth state and an electrical apparatus using the same are provided. The electrical apparatus includes a first detection unit for detecting whether there is power between a power supply line L and an earth line G and outputting a first detection signal, a second detection unit for detecting whether there is power between a neutral line N and the earth line G and outputting a second detection signal, and an earth state determining unit for determining an earth state according to the first detection signal and the second detection signal and determining whether a power supply is connected in a normal phase or a reversed phase.