"Chris J Dixon" wrote in message
...
The Main Transformer is basically a large tank in which the core
and windings sit in oil for cooling and insulation. At the
highest point in the tank is a small chamber designed to collect
any gas present. Once a certain amount of gas has accumulated,
this is detected and the unit is locked out by the software.


snip

Pardon me for de-lurking like this, but here's an interesting link about
transformer oil gas analysis:

http://www.chem.agilent.com/cag/peak...ansformer.html

.... interesting if you are into chemistry, at any rate.

Steve