Author(s): Kozupa Michal, Kolusz Grzegorz, Ploetner Christoph, Swiatkowski Michal
Electrical apparatus such as transformers radiate noise which is almost completely harmonic in its frequency characteristic and stationary in the time domain. Those two parameters enable us to look at the transformer noise through its vibration pattern of the tank wall structure. In contrary to calculating sound radiation efficiency from noise and vibration data, using only vibration data has a big advantage - the results are independent of ambient noise and acoustic parameters prediction can be performed on the design stage. However, no standards describing this approach are available at the moment. Laser Doppler Vibrometry (LDV) technique is used to identify vibration velocities of the transformer tank. The LDV measurement is non-contact and therefore the tested surface remains not influenced during the measurement. This is a big advantage of the method which provides capability for power products to be energized during the test. Eventually, the device can be measured directly during its operation and the vibration pattern information is much more reliable. Three methods of calculating acoustic radiation efficiency parameter are tested and evaluated on 250 MVA power transformer. Comparison in between methods and results for transformer units conclude the research.
Name: Dr Michal Kozupa