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Generator Loss of Excitati** Relay (40G).
Generator Loss of Excitati** Relay (40G). Electrical Generator is the main source of Electricity at Power Plant, we should make a many methods to protect the Generator from any faults can happen while Operati**. The next figure shows the main single line diagram and Protecti** Scheme for the Generator. The Generator made by Mitsubishi Heavy Industries (MHI) and its specificati** as follows: Power-------------- 440 MVA Power Factor----- 0.85 lag Line Voltage------ 19 KV Frequency--------50HZ Speed-------------- 3000 rpm Hydrogen (H2) Gas Cooled @ 4.5 barg. If a Synchr**ous machine losses the Excitati**, the following c**diti** will occur: -When partial or complete loss of Excitati** occurs ** a synchr**ous generator, Reactive power flows from the other generator into the generator. -The KW is c**trolled by the Prime-Mover input, while KVAR output is c**trolled by the Field Excitati**. If the system is large enough to supply the deficiency in Excitati** through the armature, the synchr**ous generator will operate as an inducti** generator, supplying essentially the same KW to the system as before the loss of Excitati**. -Since Synchr**ous generator is not designed for asynchr**ous operati**, the machine output will oscillate slightly as the rotor oscillates in an attempt to lock into synchr**ism. -Loss of Synchr**ism does not require immediate tripping unless there is an accompanying decrease in the terminal voltage that threatens system stability; it generally takes at least 2 to 6 Sec. to lose synchr**ism. Generator capacity-------440000KVA Generator Voltage--------19KVA CT turns ratio-------------18000/5=3600 VT turns rati**-----------19000/100=190 Gen. Transient impedance--------Xd’=24.8% Gen. Synchr**ous impedance----Xd=195% Relay Side Impedance Z=Z% * ((KV2 * 10)/KVA) * (CT ratio/VT ratio) 1-Circle #1 Diameter Z=100 *((192*10)/440000)*(3600/190) = 15.55 Ω 2-Circle #1 Offset Z=24.8 *((192*10)/440000)*(3600/190) = 1.93 Ω 3-Circle #1 Diameter Setting=15 Cycles (0.3 Sec.) 1-Circle #2 Diameter Z=195 *((192*10)/440000)*(3600/190) = 30.31 Ω 2-Circle #2 Offset Z=24.8 *((192*10)/440000)*(3600/190) = 1.93 Ω 3-Circle #1 Diameter Setting=75 Cycles (1.5 Sec.)
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آخر تعديل بواسطة Khaled Hamza ، 12-22-2010 الساعة 03:49 PM |
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مشكور على الكتاب
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العلامات المرجعية |
الكلمات الدلالية (Tags) |
(40g)., excitation, generator, loss, relay |
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انواع عرض الموضوع | |
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المواضيع المتشابهه | ||||
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