PTO generator at max torque or max HP?

[Sawyer Rob]

Lets not forget the OP was considering using a small tractor to run a PTO generator that is rated to need more horsepower than he has available, so limiting the load and the effectiveness of the tractor's governor are the major considerations in his application.

The governor has nothing to do with it, the fact that he has "too small" of a tractor to do what he wants to do, does.

SR

 

[Mudfarmer]

Using total energy used (kw-hrs) to determine an “average” power usage means nothing when sizing a generator, or any electrical sizing problem. Instantaneous power required is the only thing that matters.
Example: I want to run my 4000watt hot tub on a generator. It only runs 3 to 6 hours a day (12-24 kw-hrs per day). That’s an average 500-1000 watt load for 24 hours, so a 1500 watt generator should be more than enough right?
Or, say it is “daytime loads” for 12 hours, like you did, and we say the average is double: 1000-2000 watts, we buy a 3000watt generator? Still won’t work.
A generator needs to be sized based on running loads and to accommodate motor starting inrush currents. It has to be sized to start that motor when other loads are already running unless there’s a plan or interlocks for sequenced starts.

Or you can decide not to run the hot tub when the power is off (kinda like I turn off the heat pump) and turn all the appliances off at the breaker box (or use their off buttons) and turn them on one at a time. I presume we are talking about a temporary inconvenience.

 

[CobyRupert]

Or you can decide not to run the hot tub when the power is off (kinda like I turn off the heat pump) and turn all the appliances off at the breaker box (or use their off buttons) and turn them on one at a time. I presume we are talking about a temporary inconvenience.

Hot tub was an example. Consider any large load that cycles. If it runs say 50% of the time, but you’re using your monthly cumulative kw-hrs (and number of hours in that month) to back-track calculate what your average running load KW’s are, it’s meaningless. Your real running load (that the circuit or generator needs to be sized for) is 2x this.
If the load runs 1/3 of the time, the running load will be 3x the average you calculate. If it runs 1/4, real running load will be 4x the average , etc..
That’s the way “averages” work (or don’t) when there’s a lot of time the number is zero (or close to).

It’s like when you hear the average household income is “x”. When the CEO makes 10 million and his workers make $25,000, he can claim the “average” employee salary is $100,000.