1
SUBJECT PAGE
1. General Information....................................................................................................................3
2. Description..................................................................................................................................4
3. Method of Operation..................................................................................................................4
3.1 Components of the System....................................................................................4
3.2 Neutral Grounding Resistor Monitoring................................................................5
3.3 Ground Fault Detection...........................................................................................5
4. Installation Instructions..............................................................................................................6
4.1 The SIGMA-MD Monitor Relay...............................................................................6
4.2 Zero Sequence Current Sensor (ZSCS)................................................................7
4.3 Ngrs-XX Sensing Resistor......................................................................................8
4.4 Configuration of SIGMA-MD Monitor Relay and NGR .......................................8
5. Trip Relay and Auxiliary Fault Relay..........................................................................................9
6. Led Indicators and Diagnostics...............................................................................................10
6.1 Start-Up and Reset Indications..............................................................................10
6.2 Power on Led (Green)..............................................................................................11
6.3 Ground Fault Led (Red)...........................................................................................11
6.4 NGR Fault Led (Red)................................................................................................11
6.5 Zone Ground Led (Red)...........................................................................................12
7. Self-Test......................................................................................................................................12
8. Relay Settings............................................................................................................................13
8.1 Trip Relay Operating Modes....................................................................................13
8.2 Trip Memory Setting.................................................................................................14
8.3 Ground Fault Trip Time Delay..................................................................................14
8.4 Ground Fault Trip Current Level
.............................................................................15
8.5 System Frequency....................................................................................................15
8.6 NGR Set Let-Through Current.................................................................................15
9. SIGMA-MD Monitor Relay Configuration Switches..............................................................15
10. Technical Specifications..........................................................................................................19
11. Catalogue Numbers.................................................................................................................22
Appendix A High-Pot and Dielectric Testing................................................................22
Appendix B CAN/CSA M421-00 Use Of Electricity In Mines (Excerpts)...................23
12. Applications Examples ...........................................................................................................23
TABLE OF CONTENTS
