Leakage Detection System for Ungrounded Electrical Equipment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preventing electricity leakage from electrical equipment surfaces, such as RCDs and voltage monitoring systems, fail to effectively address leakage caused by insulation deterioration or erroneous wiring, and may not function correctly if power supply wiring is faulty, potentially leading to harm if a person touches the energized surface.
Innovation Solution
A system that detects electricity leakage by monitoring the current between the equipment's neutral line and surface, using preset current channels to trip the power supply before a person contacts the surface, and ensures the amplification and execution circuit receives power through a separate channel, even in faulty wiring conditions, thereby preventing electrical shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer and voltage comparator are used to monitor voltage between equipment surface and neutral line, then leakage detection capability is improved, but the system cannot function if power supply wiring is faulty (live line and neutral line swapped)
Solution Approach 1:
The amplifier circuit is designed to obtain working power from multiple possible sources: normally from the power supply's neutral line, but alternatively from the equipment's neutral line or equipment surface when wiring is faulty. This multi-source power configuration enables the system to function universally under both correct and faulty wiring conditions.
Solution Approach 2:
The system continuously monitors the voltage between equipment surface and neutral line in advance, and preset current channels are configured beforehand to provide alternative power paths. When wiring faults are detected, these pre-configured channels immediately activate to maintain system operation without interruption.
2Reliability
If RCD is used to detect residual current, then leakage protection is improved, but the system requires a person to touch the energized surface to generate tripping current
Solution Approach 1:
The system performs preliminary detection of leakage current through the preset current channel between equipment surface and neutral line before a person can touch the energized surface. The amplifier circuit continuously monitors this current, and when it exceeds the preset threshold, the execution circuit immediately disconnects power supply, preventing human contact with energized surfaces.
Solution Approach 2:
The patent introduces an intermediary measurement channel (preset current channel) that detects leakage current indirectly through the relationship between equipment surface and neutral line, rather than requiring direct measurement through a human body. This intermediary approach enables detection without exposing humans to electrical hazard.
3Ease of operation
If the amplifier circuit obtains power from the power supply, then the system can operate under normal conditions, but the system fails to work if power supply wiring is erroneous
Solution Approach 1:
The amplifier circuit is designed with universal power acquisition capability, able to obtain working power from multiple sources: normally from the power supply's neutral line, but alternatively from the equipment's neutral line or equipment surface when wiring is faulty. This ensures continuous operation under various wiring conditions.
Solution Approach 2:
The system uses itself to provide working power under faulty conditions. When the power supply's neutral line is erroneously connected, the amplifier circuit automatically switches to obtain power from the equipment's neutral line or surface, enabling the system to serve itself and maintain operation without external intervention.
4Object-affected harmful factors
If a ground wire is connected to pass leakage current to earth, then safety is improved, but many cases the equipment outer surface is not well grounded
Solution Approach 1:
The patent introduces an intermediary measurement channel that monitors the voltage relationship between equipment surface and neutral line. This intermediary approach enables leakage detection without requiring direct grounding connection, making the system applicable to both grounded and ungrounded equipment.
Solution Approach 2:
The system provides universal protection for both grounded and ungrounded equipment by using the neutral line as a reference potential. The amplifier circuit can detect leakage current through the preset channel regardless of whether the equipment surface is grounded, enabling the system to function universally across different grounding conditions.
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 system effectively detects and prevents surface electricity leakage before a person contacts the equipment, ensuring the power supply is cut off quickly and safely, even in cases of faulty wiring, and operates reliably by obtaining power from the power supply itself, reducing the risk of harm.
Implementation Method 1
The principle of a RCD is to use the live line (three-phase or single-phase) and the neutral line as the primary winding of a current transformer, in normal situation, the inflow live line current is equal to the outflow neutral line current therefore the residual current is zero and the corresponding secondary output voltage of the transformer is zero too.
Data Source
AI summary
Disclosed in the present invention are a method of electricity leakage detection and prevention of electrical equipment's outer surface and system thereof. The method and system are used for detecting and preventing electricity leakage of the electrical equipment's outer surface caused by defective insulation and power supply connection faults. Without in touch with the electrical equipment's outer surface, the electricity leakage of the outer surface can be detected and the connection between the electrical equipment and the power supply can be cut and an alarm is made by means of the current channel (2) formed between the electrical equipment neutral line (N′) and the electrical equipment's outer surface (G′) and the monitoring of the current value. A power supply channel (5) is set up to make sure that the electrical equipment can be normally operated via the system even in the condition of the power supply connection faults. According to the method and system, the electricity leakage of the outer surface can be correctly detected and the alarm can be made or the connection between the electrical equipment and the power supply can be cut even if the electrical equipment's outer surface is not grounded. With the advantage of simple construction and low cost, the system can be widely used.