100% Stator Ground Protection Module

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The Multilin GPM-S stator ground protection module works in combination with the Multilin G60 Generator Protection System to provide 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 GE’s Multilin industry leading G60 Generator Protection System

• 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 superior generator protection

• Increase generator lifespan by easily upgrading your current G60 generator protection relay with the 100% Stator Ground Protection Module

• Simplified setup and configuration using EnerVista setup software

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Applications

• Medium to large generator applications

• Generators with high impedance grounding

• Deployable with redundant generator protection systems

• Suitable for unit transformer connected systems

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Protection & Control

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Stator Ground Protection Module:

​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.

Key components of the ground protection scheme:

• G60 Generator Protection System

• 20Hz Injection Module: GPM-S-G

• Coupling Filter: GPM-S-B

• CT: ITI Part # 204-SD-43737

• Sensitive ground CT/VT module in G60

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G60 Generator Protection System

​The G60 Generator Protection System provides comprehensive protection for medium and large generators, including large steam and combustion turbines, combined-cycle generators and multi-circuit hydro units. The G60 includes advanced automation and communication capabilities, extensive I/O options, and powerful fault recording features that can simplify postmortem disturbance analysis and help minimize generator downtime.

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20Hz 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.

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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.

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