Join Date: Apr 2012
Location: Raleigh, NC
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Re: eight kilowatts
If a generator produces 4.4 kilowatts @ 238 volts, 60 Hz, will it produce 8 kW @ 120 volts, 60 Hz?
I was having a discussion with an electrician today who says not. He also said that the Onan 8 kW Genset rated @ 8 kW driven by a 10.5 hp diesel engine cannot possibly produce more than 6 kW.
All MDKD Onan gensets are rated as 8 kW units @ 1800 rpm and it seems as though there must be something wrong with either this gentleman's math or Onan's rating of 8 kW.
HP and wattage are both measures of power, one electrical and one physical but can be directly converted.
Your electrician friend is correct 1 hp is 745.69 watts so at 10.5 hp the max wattage it can produce is 7829.745 that is assuming 100% conversion of power between mechanical power, hp, and electrical power, kw. Onan is over stating the generators output by rounding to the nearest thousand, at 10.5 hp the maximum it could produce, without loses and assuming 100% conversion is the above stated 7829.745 watts. No diesel generator can convert 100% efficiently from mechanical power to electrical, so in my opinion this is just Onan overstating the engines ability if it is true. When I did a check of Onan generators online the 8 KW models had 22.3 hp engines attached.
By the way for your first example, assuming the generator is capable of multiple voltages it would produce 4.4 KW, half the voltage but twice the amperage, as wattage = voltage X amperage.
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Last edited by CVAT; 03-13-2019 at 03:00 AM.