AVK Alternator 1240 kva Type DIDBN 130H/10

Start here: Newage-avkseg - Frontier Power Products contact their field engineering department.

Or, read the troubleshooting section of the operators manual.

Or, hire a service tech to come and look at it.

Or, call the re-winders and ask them for help.

Seems like you did everything but determine the root cause of the original failure. As you can see if you don't figure out what went wrong how can you possibly know that you've fixed it? Hire some competent engineers to assist you.

yes sir , I shall explain what was the main cause to burn first, the non drive end bearing landing area, bearing no#nu 232 c3,was seized there, the true size is 160 mm ,but it was 156 mm then the rotor rubbed and the main rotor,excitation rotor,excitation field and aux excitation winding also burnt while running,then I examined the air gap before disassemble there was no air gap bottom side ,that was the cause to burn first, we have not changed the genuine data ,we followed the genuine data to rewind the alternator ,hope this will find good response from you,thanking you ,yours faithfully ,zen

Thanks for the feedback. Seems odd that undersized bearings, which is a purely mechanical problem, would lead to total failure of nearly everything associated with the electrical side of of the excitation system. And how did the unit pass any of your initial acceptance and commissioning tests with tight bearings? Something does not add up...

There may be a ground fault somewhere, but twice??? Let the factory technicians take over the entire repair through re-commissioning this time.

Zen Zen,

the cause of first failure was Bearing Failure.. Rubbing of Rotor and Stator.. Localised Heat Generation and the Winding Failure..

You have rectified the Bearing Fault and rewound all windings and recommissioned the Alternator..

You just said about the synchronising this Alternator with the otherone, after synchronising you have observed unusual behaviour like over heating, vibration and undesirable Noise... all these indications shows that the synchronising is not properly done.

you have found the Excitation system (Main Rotor, Exc Stator and Rotor) of the alternator burnt. this necessarily means that after synchronising the KVAR sharing between the generator is not properly done. This generator is loaded with Low Lagging PF and the other might have been loaded with sligntly leading PF.

We have seen such incidences where the Excitation system of the Alternator gets overheated due to poor KVAR sharing between synchronised Alternator..

Please take care during sync....

Regards,

Vishram LELE

Normally there are quality check / inspection sheets which record all clearances, gaps and other parameters (these sheets are prepared by quality assurance in consultation with design department) and filled by assembly department. If this practice is followed then perhaps such mishaps could be avoided.