PTO driven generator for standby power: What say you?

RobJordan · Apr 21, 2007

Has anyone used a Mahindra in the 18-26 hp range to power pto driven standby generator? Been thinking of getting one for standby power at the house. The concern I have is whether you have to have a governor link-up to the generator to accomodate changes in power loads. With a bigger tractor 40+ hp and a smaller generator (say 7.5 to 10kw) the tractor could handle load changes just fine. I'd like to marry a 18-24 hp Mahindra to a 7.5 kw pto generator. Any experience with a similar set up is appreciated.

Thanks,

Jordan

VistanTN · Apr 21, 2007

No personal experience, but an electrical engineering degree and a lot of tractor experience says you need to consider:
1. PTO HP is only about 75% of gross tractor HP
2. 1 HP = .75 KW
3. No generator is 100% efficient (80% is very good, some run as low as 50% or less)
4. Unbalanced electrical load loads the generator (increased inefficiency) more than the average of the two legs if balanced.

Taking the average of your cited HP (if it is gross as opposed to PTO HP), 21 gross HP = 11.8KW at the PTO -- best case that will power about a 9.5 KW generator fully loaded with a balanced load.

What is probably equally important if not more so is how the engine reacts to a sudden increase in load. That's dependent on engine condition, and a bunch of other factors like how big, how sudden, etc. If its just the surge (transient) current of a motor start up, that's different than if its a steady state change.

Your proposed setup should be OK, but without knowing what electrical loads you have and what condition your tractor is in, I can't say it will be "just like the electric company."