Of course it all depends on what you are trying to achieve.
Maximum peak power of course!!!Â
I tend, based on experience, to think you are very much correct about oversizing the generator set. I know for a fact how hard these circuits are on everything. No sooner do you beef up the weakest component in the system (because the previously engineered component failed in serivce), then the next weakest component in the system fails... When the step up transformer, tank circuit and gaps are all pretty much bullet proofed, the next place to look for a failure would logically reside in the control cabinet & power supply.
I am hoping to keep the actual design, research, and prototyping power levels in the range between 3-6 kW, and figured on installing an ST15kW generator head for the mains supply. I could do an ST20, I held back at the last second on the genhead purchase because I have no place to store it until the shop/lab building is roofed and that is a few weeks away yet. There is a lead time in importing the engine, so I paid for that and held the check for the ST15 back.
There is the inevitable temptation in this line of research to match a larger engine to a larger generator and anybody familiar with this equipment knows there is an infinity quotient directly associated with Tesla's resonance patent... There is no limit to how large and powerful this equipment can be scaled up to. It can lead to bankruptcy.
I have designed, built, and operated Tesla oscillators and resonators in the 10-15 kW range, and having done this I am of the opinion that this is 2-3x above the power levels needed in order to produce viable prototypes and demonstrations of the new applications I have patented. Most of the time I think 3 kW of input power should do the trick, and if it doesn't then 6 kW surely will make my points.
I have liquidated, or am in the process of liquidating, practically all my assets to put this project together... I have the money required to do the job right, but the sky is not the limit. With this in mind, I sized the power plant for dual use... It will run the ranch most of the time, and it will power the research for a small fraction of the time. Giving the balancing act required whenever a project like this is designed, engineered, and paid for... I opted to go with a 20 HP prime mover to turn the generator, and a 15kW ST. I would not consider spending a few hundred extra on an ST20 to be extravagant.
The goal here with the Tesla research is to design, engineer, and prototype patent models for commerical development... Not the commerical applications themselves. Admittedly, I could probably do this work on a much smaller scale, and could even use solid state oscillators... But it would not give people the picture of what a commerical type installation and application would look like... In other words, the proofs can be done on apparatus you can probably hold in your hand and plug into a wall outlet... But in my experience people have limited imagination and are not able to see that scaled up equipment operates on exactly the same fundamental physics, only everything is larger.
So in effect what I am doing is developing a research facility as a scaled down mini-plant... Fuel will come in, drive the prime mover, spin the jackshaft with flywheels and turn the generator.... It will have all of the basic components of a stand alone commerical enterprise, just on an R&D scale.
Good capacitance is expensive... I have some good capacitance with low minutes, and it has never been excited at anywhere near its rated voltage and capacity... They were designed to be tough enough to process 20 kW all day, and should have 72 hours of life in them at 40,000 volts AC rapidly pulsed. I should be able to get many, many research hours out of them at much lower voltages and power levels.
If I were to decide to go with a much larger generator, I would end up moving to higher power levels. If I were to do this I would convert the main oscillators over to 3 phase and pick up a used commerical 3-phase generator to drive it. I suppose this is possible eventually, I have thought about it, but it is not in the cards at this point. I think perhaps what I may do is put some extra floor space in the engine room, leave a blank spot in the floor where a mounting block for this upgrade could be placed in the future... Then, if I see a steal deal on a big 3 phase generator...
But I would not remove the Listeroid and ST genset from service... I still need a primary power supply for the ranch.