Microbubbling in transformer oil due to vibration

Vibration is a prevalent process in oil filled power equipment, especially in transformers and electrical reactors. The most common cause of vibration is an alternating action of magnetic forces. If vibration takes place in narrow gaps, pressure inside gap increases and decreases periodically. In some cases pressure becomes negative, which could lead to bubble appearance and gas generation. Experiments and calculations show that there is cavitation inside non-magnetic microgaps. In case of non-degassed transformer oil microbubbles appear inside gap, dash out of gap and then float due to buoyancy force.