Insulation Resistance Monitoring for Bipolar DC Neutral Ground Faults
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Solution Overview
Problem
Conventional insulation resistance monitor devices for bipolar DC power systems are complex, costly, and unable to measure insulation resistance between the neutral line and protective earth, necessitating a more efficient and comprehensive solution.
Innovation Solution
A DC power system with a positive line, neutral line, negative line, and protective earthing terminal, equipped with a first resistor, sensing resistor, and detection circuit to measure sensing voltage across the sensing resistor, allowing detection of insulation degradation or failure between these lines and the protective earthing terminal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional insulation resistance monitor devices use multiple resistors and switches to measure insulation resistances, then the measurement capability is provided, but the device complexity and cost increase
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated circuit that uses only one resistor and one switch. The insulation resistance monitor device integrates the measurement of insulation resistances between positive line and protective earth, negative line and protective earth, and neutral line and protective earth into one unified device, eliminating the need for separate resistors and switches for each measurement.
Solution Approach 2:
The single resistor and switch in the insulation resistance monitor device serve multiple measurement purposes. The same components are used to measure insulation resistances between different lines and protective earth by switching between different measurement configurations, making the device universal and multi-functional rather than requiring dedicated components for each measurement.
2Device complexity
If conventional insulation resistance monitor devices are designed for DC power systems with only one DC source, then the design is simplified, but the ability to measure insulation resistance between neutral line and protective earth is lost
Solution Approach 1:
The insulation resistance monitor device is designed to universally handle both DC power system configurations - systems with one DC source and systems with two DC sources. The device maintains the same simple structure with one resistor and one switch while gaining the capability to measure insulation resistance between the neutral line and protective earth in bipolar DC power systems, achieving both design simplicity and comprehensive measurement coverage.
3Measurement precision
If conventional insulation resistance monitor devices use multiple resistors and switches for separate measurements, then the measurement procedure is established, but the cost increases
Solution Approach 1:
The patent merges multiple measurement functions into a single cost-effective device. By combining the measurement of all insulation resistances (positive line to protective earth, negative line to protective earth, and neutral line to protective earth) into one device with a single resistor and switch, the manufacturing cost is significantly reduced compared to conventional devices that require multiple resistors and switches for each measurement function.
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 accurately detects and distinguishes insulation degradation or failure between the positive, neutral, and negative lines and the protective earthing terminal, enhancing safety and reducing complexity and cost.
Implementation Method 1
The first detection circuit is electrically connected to the first and second terminals of the first sensing resistor, and is configured to measure a sensing voltage across the first sensing resistor and detect whether an insulation resistance between the protective earthing terminal and any of the positive line, the neutral line and the negative line is abnormal according to the sensing voltage
Data Source
AI summary
A DC power system and an insulation resistance monitor device thereof are provided. The DC power system includes positive, neutral and negative lines, a protective earthing terminal and a grounding resistor. The grounding resistor is electrically connected between the neutral line and the protective earthing terminal. The insulation resistance monitor device includes a first resistor, a first sensing resistor and a first detection circuit. The first resistor is coupled to the positive or negative line. The first sensing resistor is coupled between a second terminal of the first resistor and the protective earthing terminal. The first detection circuit is electrically connected to the first sensing resistor, and is configured to measure a sensing voltage across the first sensing resistor and detect whether an insulation resistance between the protective earthing terminal and any of the positive, neutral and negative lines is abnormal according to the sensing voltage.