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Stator ground module works in combination with UR G60 to provide a 100% stator ground fault protection that is operational during generator start-up, running and stopped conditions. In the 100% stator ground fault protection based on sub-harmonic injection, a 20Hz voltage is injected to detect ground faults at any point across 100% of the winding thereby protecting the complete stator winding and allowing early detection of stator ground fault conditions.

 
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Key Benefits
  • Detect ground faults through 100% of the stator winding including neutral point
  • Sub-harmonic injection based stator ground protection provides early detection of ground fault conditions
  • Designed to operate with Multilin’s industry leading G60 Generator Protection System
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  • Active protection of the generator even under machine shutdown conditions for increased asset life
  • Providing a wide range of fault resistance coverage which allows for greater generator protection
  • Increase generator life span by easily upgrading your current G60 generator protection relay with the 100% Stator Ground Protection Module
  • Applications
  • Medium to large sized generators
  • Generators with high impedance grounding
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  • Deployable with redundant generator protection systems
  • Suitable for unit transformer connected systems
  •   Key Features    
    Protection. Diagnostics
     
  • Two stage stator ground resistance based element – 64S
  • Wide range fault resistance coverage (1-20Kohms)
  • Over current element for low resistance faults
  • CT phase angle error compensation
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  • Sub-harmonic voltage supervision
  • Sub-harmonic current supervision
  • Extensive internal diagnostics in the module with critical-fail relay
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    100% Stator Ground fault Detection
  • The 100% stator ground fault protection is based on sub-harmonic injection
  • 20Hz voltage is injected to detect ground faults at any point across 100% of the winding
  • The stator ground module works in combination with the G60 to provide 100% stator ground fault protectionv
  • Operational during generator start-up, running and stopped conditions
  • Protection & Control
     
    20 Hz Injection Module
    Using sub-harmonic injection provides early detection of stator ground fault conditions. This is accomplished by the injection module generating a square wave pulse of 20Hz with a magnitude of +/-26V into the stator winding. The injection module monitors the frequency and magnitude of the signal it generates which allows for the Stator module to determine if a ground fault has occurred in the stator winding. In addition, the stator module is also equipped with a critical-fail relay that can be wired to alarm failure of the module.
    Coupling Filter
    The coupling filter is used to meet two functions: to smooth the square wave and convert it into a sine wave and to protect the injection module from AC voltage impressed from the secondary of neutral grounding transformer. Coupling filter contains only passive components. It also contains voltage divider circuits to be used on applications with NGT secondary voltage greater than 500V