How to calculate the change in watts if input voltage is changed?

[quicksandfarmer]

Power equals voltage squared divided by resistance.

If resistance doesn't change, going from 208 to 220 power increases by 11.8%. Going from 208 to 240 power increases by 33.1%.

 

[CobyRupert]

Single phase 208V generator? Or should we assume this is 3 phase given that 208 voltage is typical for 3 phase power (vs. 240V single phase) and the fact there are 3 heat elements? If so, Power= 3 (phases) x V(line-ground) x Current; or also Power= 1.73 x V(line-line) x Current. (Because V(L-G) =V(L-L)/1.73= so by substitution the 3 multiplier becomes a 1.73 multiplier).

 

[90cummins]

The heater is single or 3 phase 208v that was given to me. I rewired it so I can select 1, 2, or 3 heating elements for various loads.
My generators are single phase and the output ranges from 115~220 to 125~240.
The Dayton (Yanmar) generator I just repaired is operating at 125v loaded 130 no load.
Also what is the voltage tolerance of household appliances? Is 130v too high?
It is a brushless alternator, capacitor regulated, should the capacitor be replaced?
As mentioned in a previous post I will measure the voltage & current in the separate legs to actually determine the load.
I will also measure across the hot leads to find what the high voltage is, 220/240???
Appears my question cannot be answered without more info. But it would be nice to be able to calculate the watts and increase in voltage causes.
Thanks for the replys.

90cummins

 

[doxford jim]

Do you have a clamp on meter ? It would be easy to use and will give you the readings on any wire you clamp the meter on.
Using Power=volts x amps relation (pf=1) will give the power used/generated for each cable/wire.
I picked up a cheap Chinese copy of a clamp on meter (very cheap) and it works for my needs.

 

[90cummins]

No! Sounds like I should pick one up.
It would eliminate these hard to answer questions..
90cummins

 

[hr3]

What type of repair are you doing on his generator if I may ask ???

 

[90cummins]

I purchased this Dayton (Master) 5000 watt generator in 2009 that had an L90 Yanmar diesel with 577 hours on it that the owner thought had a cracked head.
A teardown found that the leak was a bad injector seal but I also found a broken piston ring land that possibly happened by using starting fluid.
I was slowly acquiring parts when I recently found a New Military Spec. L70 Yanmar with an extended 3qt deep sump, bypass oil filter and grid heater.
I purchased this with the thought that although it was a smaller engine it should still meet my minimum needs and also reduce the fuel consumption.
Yanmar describes this engine as being capable of running nonstop without attention for 500 hours.
The purpose of my post was to put a specific load on the generator and do a fuel consumption test and compare it to my Generac XL4000 gas generator.
On the initial trial run I ran the heater for 32 minutes on 1 quart of diesel.
I also have an L100 Yanmar that I’m also in the process of repairing and I recently purchased a Yanmar YDG 3000 Diesel generator that also needs (unknown) repair.

90cummins

 

[90cummins]

I measured the voltage across the 2 hot leads and have 260v no load and 250v loaded.
The Yanmar manual specifies no load voltage of 132v max/ 265v max.
The operating range for 120v is 122+-3
The operating range for 240v is 244+-6
According to the manual I'm good to go.
What do you think??
What damage can high voltage do to home electronics?
Hertz ranged from 61.3 no load to 60.3 loaded.
Thanks

90cummins

 

[BrandonR]

Most simple devices will be fine with that power output. Your frequency is a little on the high side, generally you are good between 59-61hz, dropping the rpm's a touch will drop the frequency as well but getting any closer than you already are may be impractical. Some picky electronics will not be happy being anything off 60hz but shouldn't be damaged.

 

[dave1949]

My grid-tied inverter and my Kill-a-Watt meter both consistently measure our line frequency at 59.9 Hz. That's why things move a bit slowly here. :laughing: