Can somebody tell me which are best ultrasound equipments for monitoring high voltage power transformers
With respect
Gazmend Kabashi

I use an older model SDT 150 meter and custom made parabolic sensor. The parabolic sensor gives pinpoint fault detection at greater distances. Contact vendors SDT, UE Systems, Emerson (CSI) and others. Be sure that you have salesman give a demonstration and provide appropriate application notes or procedures. He is a link to SDT in Belgium:
http://www.sdt.be/index1.html

Walt