Yes it is but my first question would be what is the application? The most direct way to get more than 300VAC is to buy a 3 phase AC source. The voltage maximum is 300VAC phase to neutral so if you measured between line to line it would be 1.732 times larger (square root of 3) which is 519VAC. This may be severe overkill for your application. If you already have an AC source and the power requirement is not too high you could use a step-up transformer on the output of the AC source to get higher voltages from a single phase unit.
thanks for answer :)
best regards