rotor testing

[zub]

Who knows something about "recurrent surge osciloscope measurement method" will be done on the rotor of synch. generator?. Would you like to share your knowledge with me?

thanks.

zub.

 

[rhatcher]

It sounds like your are referring to a 'surge comparison test'. This test compares the inductance of the two windings under test by sending voltage pulses through the windings. The resulting inductive response is displayed on an oscilloscope with the two patterns overlayed. If the patterns match then the inductances match and it can be assumed that there are no turn-to-turn shorts in either winding.

To apply this test to the rotor of a synchronous machine, you must (assuming series connection) find the center point of the rotor circuit and compare each half of the winding. This test is similar to a voltage drop test in that it will determine if there are any shorted coils.

 

[electricpete]

rhatcher is right on the money as usual. One other trick if you don't have two identical points for comparison is to test one point against itself with different voltages. Overlay the traces from multiple runs at different voltages and the zero-crossings should not change.

But beware. It may be considered a destructive test if the windings are already weak or if the test is not done properly. Selection of voltage is important... too high can fail a good winding.... too low may not detect a marginal winding.

Try searching for Baker motor surge tester.

 

[jbartos]

Suggestion: Visit

http://www.irscoil.com/qualitycontrol.shtml

http://www.joliet-equipment.com/rebuilding_process.htm

(indicates when it is done during the rebuilding process)
Also, see
Nailen, Richard L., "Understanding Surge Comparison Testing," Electrical Apparatus, Vol 48, No 12, December 1995, pp 27-31
The above testing is for variation to diagnose an insulation condition. Also, it reveals improper winding connections, unrelated to dielectric integrity.