TIDUEZ8C december   2022  – june 2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Insulation Monitoring
    2. 1.2 Impact of Parasitic Isolation Capacitance
    3. 1.3 IEC 61557-8 Standard for Industrial Low-Voltage Distribution Systems
    4. 1.4 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 TPSI2140
      2. 2.2.2 AMC3330
      3. 2.2.3 TPS7A24
      4. 2.2.4 REF2033
      5. 2.2.5 TLV6001
    3. 2.3 Design Considerations
      1. 2.3.1 Resistive Bridge
      2. 2.3.2 Isolated Analog Signal Chain
        1. 2.3.2.1 Differential to Single-Ended Conversion
        2. 2.3.2.2 High-Voltage Measurement
        3. 2.3.2.3 Signal Chain Error Analysis
      3. 2.3.3 Loss of PE Detection
      4. 2.3.4 Insulation Monitoring on AC Lines
      5. 2.3.5 PCB Layout Recommendations
  9. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1 Connectors
      2. 3.1.2 Default Jumper Configuration
      3. 3.1.3 Prerequisites
    2. 3.2 Software Requirements
    3. 3.3 Software
    4. 3.4 Test Setup
    5. 3.5 Test Results
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  11. 5About the Author
  12. 6Revision History

3.5 Test Results

Figure 3-3 and Figure 3-4 show the relative error for the 400-V and 800-V tests. The color scheme in the tables from green over yellow to red shows the small to big relative errors and is used to indicate performance in different areas of the measurement range. The test results show that the measurement accuracy is best in the important range of 20 kΩ to 200 kΩ, where the insulation faults must be detected. With higher insulation resistance values, the accuracy falls off, especially above 1 MΩ. This reduction in accuracy is not a problem since in this range the insulation is far above the fault and warning levels. For this reason, the actual software for this reference design does not return values above 1 MΩ. Every calculation result which indicates a resistance higher than 1 MΩ is set to 1 MΩ. This feature was disabled for the measurements in the following tables.

GUID-20220929-SS0I-L3HM-FCTQ-KT5DX32KNSQQ-low.png Figure 3-3 Accuracy 400-V Test
GUID-20220929-SS0I-DVGM-0KDP-J29P1TBQDCJR-low.png Figure 3-4 Accuracy 800-V Test