Abstract
Utilities employ Thermal instability testing (TIT)
for final acceptance testing after the construction and
refurbishment of turbogenerator rotors. This type of testing is
performed through two methodologies namely current injection
and friction/windage in order to assess the thermal sensitivity of
the machine’s rotor. Although there are distinct differences
between the two methods, no apparent preference is shown by
service providers/OEMS globally. There is also no definitive
evidence or standards that offer a comparison of the two methods
and suitability assessment thereof. The presented research
investigates these two methods of TIT for a synchronous
generator rotor. An experimental setup with infrared
thermography is employed to investigate the thermal behaviour
of the machine’s rotor for each of the test methods. Experimental
results show that the thermal behavior of the generator rotor is
significantly different for each methodology. It is also shown in
this paper that contemporary TIT practice requires an
augmented test methodology.