12-22-2010, 05:27 PM
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عضو فعال
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تاريخ التسجيل: Aug 2010
الدولة: Egypt
المشاركات: 68
معدل تقييم المستوى: 14
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Generator Stator Earth Fault Relay .
-For high impedance grounded generators, a voltage relay across the sec**dary winding of the Generator neutral grounding transformer is used to detect the ground fault ** the generator stator winding.
-The neutral over voltage functi** (59N) resp**ds to the fundamental frequency voltage at the generator neutral that appears when a ground fault occurs.
-Normally, it will protect up to 90≈ 95 % of the stator windings.
-The neutral under voltage functi**s resp**ds to 3rd harm**ic voltage measured at the generator neutral. When used in c**juncti** with the neutral over voltage functi**, it provides 100% ground fault protecti** of the stator winding.
-In healthy state, the machine 3rd harm**ic voltage is distributed over the windings such that the maximum occur at the star point neutral and at the line terminal. For a ground fault close to the neutral, all the 3rd harm**ic voltage is transferred to the line terminals. C**sequently, the relay functi** will see a 3rd harm**ic under voltage at the neutral end and will operate the protecti** element.
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