I would like to tie several generators together to output to a single output wire. Is there a formula that will let me know what the out put would be? Is this possible? and what happens with different voltages? What would be the disadvantages?
The total power would be the power delivered by each generator added up.
I am no expert in paralleling sources but some of the things you have to consider is synching the generators together so that all cross zero at the same point. There are relays for this but breakers on each would be required (might be anyway by NEC). Also, the voltage amplitude should be considered in your decision to tie to generators together (make sure equal before tying together)(like an AVR or something). What your purposing is doable and done all the time (think of the grid). There are many considerations that should not be overlooked or serious damage or even death could occur when you attempt to tie these together and they are not in synch (generator trailer may even roll for you).
There are many in here that I am sure will add some more considerations as well as elaborating on my concerns. Good luck.
What you are asking is possible. In fact, virtually every utility in the world does this exact thing.
If run isolated from a utility 'grid', one (best if the largest) of your generators needs to be able to govern the frequency of the isolated system to, say, 60Hz.
This is a very complex topic, and I strongly recommend the services of a competant engineer experienced in this area before you commit any real $.
Assuming all generators are compatible (or made to be compatible via transformers), the total output would be the sum of the rated outputs of the individual units at the actual frequency and voltage (less any losses).
