I have not managed to get the phases swoped over yet due to other constraints, I have however previously checked the harmonics
3.7% peak 5th with long durations of over 3% at weekends
0.8% peak 7th
Which is not really enough to justify what is happening, however I do have suspicions about the...
Further progress
The Motors have been tested upto 2kV and found to be balanced, the voltage at the terminals with the motors running is balanced so assuming that we have not managed to cheat the laws of electricity its either a problem with the motors internal windings that manifests itself...
Thanks for the reply,
The 3rd problem which I managed to forget to include in the post is that the contactos feeding the blowers are burning out even though thay are oversized.
I have checked the resistance of the windings including the feed cables and found them to be the same, the voltage...
This one has now eluded me!
3 control panels each seperatly feeding multiple blowers with 132kw Star Delta startup motors. Three problems noted to date:
The cables to the motors vibrate (100hz on 50hz supply deffinatly not mechanical vibration)
The motors have a phase imblance - 1 winding...
