Recurrent Surge Oscillograph (RSO) Test

A short rise time pulse is injected into the rotor via the slip rings.  Initially the pulse is injected from one slip ring only to enable a measurement of transient time to be taken which is used later to assist with the location of any fault that may prove to be present.  Source impedances of the pulse generator are adjustable to ensure the connections from the generator to the slip rings have negligible impact on the result.

The pulse is then injected and measured simultaneously from both slip rings; the resultant pulses are then subtracted to gain a differential pulse with any peaks in the differential being an indication of a shorted turn or an earth fault.

RSO tests are conducted off-line at a range of speeds which allows the influences of the mechanical stresses on the rotor winding insulation to be measured and allows any developing faults to be monitored.

This test is most sensitive to inter-turn insulation faults, or shorted turns on generator rotors.
It can also be used to detect Open Circuits and Earth Faults of the rotor windings.
       
Application includes: Generator and Motor Rotors