Recurrent Surge Oscillography (RSO) It is a testing technique used to detect shorted-turns by inserting a high-frequency, low-voltage waveform at both ends of the field winding, and visually evaluating the differences in the returning signals. The RSO can be used with the rotor inside or outside the stator and due to its low test voltage is safe for the inter-turn insulation and testing personnel. Megavar utilises the RTS 02 test set and an oscilloscope to enable testing according to the AEEGE and AEE100 test method.

Shorted turns in the rotor can have a range of impacts for rotating machines including-

  • increased vibrations
  • Vibrations sensitive to field current (VAR) changes
  • reduced excitation capability


RSO is typically used in the following test regimes:

  • Routine condition measurement
  • Investigation of increased vibration or reduced excitation

If you require RSO testing, call Megavar for professional service and advice.