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US 2026/0235678 A1Published application
Intermittent Ground Fault Detection For Stators in High-Impedance Grounded Generators
AssigneeWiSys Technology Foundation, Inc.
InventorNader SAFARI-SHAD
Life of this patent
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Abstract
An intermittent stator ground fault detection system employs a subharmonic injection current and monitors subharmonics above and below the generator frequency and excluding the subharmonic injection current frequency to sensitively detect intermittent stator ground faults.
Claims19
An intermittent ground fault detector for electrical generators operating at a generator frequency and comprising:
- a current injector injecting current into stator windings of the electrical generator at an injector frequency offset from the generator frequency;
- a current monitor monitoring a first current in at least one stator winding above and below the generator frequency excluding the injector frequency and generator frequency and comparing this first current to a baseline value based on a second current at the injector frequency;
- and
- a threshold detector triggering at least one of an alarm or a trip signal based on a comparison of the first current to the second current.
1 more element
An apparatus for testing an intermittent ground fault detector of a type having:
- a current injector injecting current into stator windings of the electrical generator at a subharmonic an injector frequency offset from the generator frequency;
- a current monitor monitoring a first current in at least one stator winding above and below the generator frequency excluding the subharmonic injector frequency and generator frequency and comparing this first current to a baseline value based on a second current at the subharmonic injector frequency;
- and
- a threshold detector triggering at least one of an alarm or a trip signal based on a comparison of the first current to the second current;
- the apparatus comprising:
- a current transformer having a secondary for connecting to the ground fault detector and a primary providing a voltage source switchably shunted to ground at a controllable frequency and controllable duty cycle to simulate intermittent ground faults.
3 more elements
Dependencies are inferred from the claim text.