Protective Earth Ground Circuit Detection Using High Impedance Path
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Solution Overview
Problem
Existing Earth Leakage Circuit Breaker (ELCB) systems face challenges in detecting faults in Protective Earth (PE) connections without a physical Earth connection or tangible current flow, particularly in applications like Electric Vehicle Supply Equipment where a direct conductive path to Earth is not available.
Innovation Solution
A system utilizing a high impedance device, such as a resistor, coupled across a switch, with a control system to monitor voltage across the device, leveraging natural capacitance and resistance between the device and Earth to provide an Earth connection, allowing for voltage detection without a physical connection or current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage operated ELCB (vELCB) is used to detect ground faults with negligible leakage current, then current safety is improved, but a functional Earth connection is required which limits applicability
Solution Approach 1:
The patent introduces a high impedance device as an intermediary element that enables voltage measurement without requiring a direct Earth connection. The device couples the ground conductor to the control system through a high impedance path, allowing the control system to sense voltage relative to Earth potential without needing a functional Earth connection at the measurement point. This mediator enables vELCB functionality in locations where traditional Earth connections are unavailable.
2Adaptability or versatility
If an iELCB system is used that requires tangible current flow to detect ground faults, then no real Earth connection is needed, but current flow to the device is required which violates safety standards for EVSE
Solution Approach 1:
The patent changes the operational parameter from current-based detection to voltage-based detection. By measuring voltage across a high impedance device rather than measuring current flow, the system achieves ground fault detection without requiring tangible current flow to the protected device. This parameter change enables compliance with EVSE safety standards that prohibit current flow before Earth connection verification.
3Adaptability or versatility
If a high impedance device is used to enable voltage detection without Earth connection or current flow, then adaptability is improved, but device complexity increases
Solution Approach 1:
The high impedance device serves multiple functions: it enables voltage sensing without Earth connection, limits current flow to negligible levels, and provides a coupling path for the control system. By consolidating these functions into a single component, the patent achieves adaptability without proportionally increasing complexity. The device is integrated into the existing EVSE architecture, sharing components with the charging control system.
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 safe and reliable detection of PE faults without the need for a physical Earth connection or current flow, meeting safety standards by controlling the switch system based on sensed voltage thresholds, thus ensuring a functional PE connection is verified before power is applied.
Implementation Method 1
A natural high impedance path between the Earth and the device is used to provide an Earth connection through the device during operation of the system
Implementation Method 2
A system for detecting the presence of a voltage on a ground conductor which is coupled to a protective Earth (PE) terminal associated with a power source
Data Source
AI summary
A system and method for detecting the presence of a voltage on a ground conductor which is coupled to a protective Earth (PE) terminal associated with a power source. The power source is used to apply a voltage to a device. The system may use a high impedance device coupled across a switch, with the switch being in communication with a portion of the device. A control system may monitor a voltage across the high impedance device and determine if the voltage across the high impedance device exceeds a predetermined threshold. Exceeding the predetermined threshold indicates that an unsafe voltage from the power source is present on the ground conductor. A natural high impedance path between the device and the Earth is used to provide an Earth connection through the device to the Earth during operation of the system.