Motor - Alternator Set 6.6 KV 400 HP

1. Some things not understood in your text, please explain.....
2. "winding ??clip?? flashover"?
3. "kept ??dummy??"
4. "windings... connected Start and end" - connected to what?
5. Is this a frequency conversion set?
6. Are motor rating plates/terminal diagrams identical except for serial number?

On winding resistance, 52 is near enough half of 105. So maybe 1 winding of parallel 2 [each 105] is open or one of 2, each 52 in series, is shorted. And is the "panel resistance bank" identical for both machines or different to fit different rotor resistance/voltage?

Look at circuit diagrams for machines for difference.

Slip Rotor bar construction and joints are made at overhang end , clip are used for brazing joints. Since only two winding are connected to slip rings rings 4. Third winding not connected and kept as dummy winding not connected to slip ring which may function as damper winding. Motor is 6.6 KV and alternator is 440 volts 60 cycles

No drawing is available , Name plate does not give complete information

Excitor also mounted on the same shaft to give DC Supply to feed two windings when started

It's difficult to understand everything you are describing, likely due to English being a second language for you. But it sounds to me as if maybe what you have is what's called a "doubly-fed induction generator (DFIG)". This is essentially a wound rotor induction machine that can be a motor or generator and the way the rotor is powered is very different from a standard Wound Rotor Induction Motor. Do some research on that DFIG term and see if it describes what you have.