winding movement detected
winding movement detected
(OP)
I just tested a 16 MVA unit that was subjected by 2 - 100 MVA 3-phase bolted fault on a down stream bus. One occured last week and the other occured last May.
Ratio and resitance data is normal.
Capacitance bridge data showa a 16% increase for SEC - GND capacitance an 8% increase in SEC - (PRI & GND) values.
Latest DGA shown no change. This can be expected in the movement occured on the last fault and not the faaul in May and even then. it may not be dectable by DGA analysis.
I am suggesting a SFRA test on the faulted unit and do a comparitive analysis for a SFRA test on its sistem unit.
Another DGA is expecte in one month to determine in general heating of the core may result of the winding shift.
The unit has been back in service for 1 week now.
Thoughts anyone ? and thanks.
Ratio and resitance data is normal.
Capacitance bridge data showa a 16% increase for SEC - GND capacitance an 8% increase in SEC - (PRI & GND) values.
Latest DGA shown no change. This can be expected in the movement occured on the last fault and not the faaul in May and even then. it may not be dectable by DGA analysis.
I am suggesting a SFRA test on the faulted unit and do a comparitive analysis for a SFRA test on its sistem unit.
Another DGA is expecte in one month to determine in general heating of the core may result of the winding shift.
The unit has been back in service for 1 week now.
Thoughts anyone ? and thanks.






RE: winding movement detected
That is a very good next step. Try to have the best test connections you can have.
RE: winding movement detected
RE: winding movement detected
Just to add that winding resistance did not change so no deformation of the winding cross-sectiona area were noticeable and may be suggestive that this was a minor movement which may not impact winding / insulation life.
I'll get a better feel after these test are completed.
Thanks all.
RE: winding movement detected