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1-200MW Steam Turbine Generator Care


I. Generator grid-connected without synchronization


   Before grid-connected, the voltage, frequency, phase sequence and phase position of generator should be in step with grid. But under some conditions, the client doesn`t check phase or synchronization device fault when grid connected. It causes grid-connected without synchronization and it damages generator and power systems. The generator stator will be attacked by a huge electric current under grid-connected without synchronization. The current meter will swing violently and the voltage meter will swing also.


   The huge current will severe impact on generators, transformers and the system. The STG will shake strongly and make the generator winding deformation, twisted, insulation cracked and make the end to end joint sleeve of windings melt. It will cause some serious hidden dangers even burn windings. For the whole power system, if a big STG connect to the grid without synchronization, the power shock will happen between the generator and system. It will disrupt the whole system operation normally and even make the entire power system collapse.  


Typical cases:


   This is a generator of Inner Mongolian client. The non synchronization accident occurred when the generator was on automatic synchronization. It made many tying torn apart and more than two thirds of coils insulation cracked and B-phase grounded.


   When we repaired the generator, we removed all coils and made withstand voltage test for those coils. For the non-destructive coils, we used them after cleaned up. For the failed coils in test, we treated them with re-insulation re-offline, testing, welding ends and completed factory withstand voltage test. When we inspected the relay protection system, we found the synchronization screen fault in grounding. After adjustment return circuit of sy .qnpturbines.com