Meggering of 3-phase Synchonous Generator

[speedtronic]

For phase to phase Meggering of 3-phase Synchonous Generator, we have to open its flexible links (between phases) & its star point. We then connect Megger's positive lead to phase (which we want to Megger) & we short remaining two phases with ground?(& connect megger's negative lead to it) Why?? What if we donot short other two phases with ground?

 

[Shakey]

For phase to phase Meggering of 3-phase Synchonous Generator, we have to open its flexible links (between phases) & its star point. We then connect Megger's positive lead to phase (which we want to Megger) & we short remaining two phases with ground?(& connect megger's negative lead to it) Why?? What if we donot short other two phases with ground?

erm...nothing. All you are doing is IR checking between output windings. This is the same as, say, connecting together live conductors on an installation and IR checking between them to earth. If there is a fault there it will show up if you do them connected or IR test individually

 

[speedtronic]

please tell me that for phase to ground meggering of a 3-phase power T/F. Do we need to perform same practice? I mean like shorting of other two phases to ground?
Moreover, kindly tell me something about high pot. test. I know that it is used to measure maximum voltage withstanding capability of an equipment. BY injecting high voltage, what do we measure at output? & what should be its range?
Also kindly tell me about stator winding inter-turn faults? what they actually are? As I know, In case of inter-turn winding fault the current on both side of the winding is same so differential protection can not be used? then what kind of protection is used for it?