Below are some of the instances why transformers fail.
As a general rule, when transformers are water-cooled, most of the failures occur because of a breakdown of the insulation between the windings.
Typically this is due to lack of water, poor quality water, the water-inlet temperature being too high, or operating the transformer outside of its designed rating. Insulation failure is sometimes caused by the harsh environment the transformer is subjected to.
Another failure that commonly occurs would be the melting of the output connection (fishtail). This is caused by improper tightening (recommended torque is 30 to 40 ft/lb.), or maintenance on the inductor, which includes dirty and oxidized surfaces on the mating inductor or Fishtail surface.
There are occurrences when the core fails. Again, this may be due to the lack of water, poor quality water, the input volts per turn are too high (exceeds core loss temperature limitation), and improper use of frequency.
One of the best investments you can make is in a well-designed water system. This will pay for itself with reduced component failures and reduction of downtime. Proper maintenance of the inductor and transformer connections will also help greatly.
If you have experienced a transformer failure, please check out our Repair Services page.