[bestgenman]

When regulators fail it is usually because of excessive current draw on the output (F+ F-). When the set shuts down the falling speed causes the output of the regulator to increase in order to keep the voltage up. if there is significant load, it worsens. The connected loads should either be turned off or at best reduced prior to turning off the generator set.

Also, if there are shorted windings in the excitation circuit that as well may be causing your problem. Make sure you have a fuse in the input to the regulator with an amperage size for the rated current.

I hope this helps a little bit.