re: building a generator
21 may 1999
michael chang wrote:
>> i built a box last year to place over the generator to quiet the noise...
>> it worked very good at silencing the generator, you could barely hear it
>> standing right next to it.
sounds like a lovely way to run a generator in the basement, with a little
negative air pressure inside the box and a nighthawk co detector, and a
step up variac and a couple of series light bulbs in parallel with a circuit
breaker to make the meter go backwards.
>> but the temperatures inside the box were in excess of 120f.
sounds good, if we want to use some of the "waste heat" (80% of the fuel's
heating value :-) for house or water heating. a $900 90 pound 1500w gasoline
honda generator makes 1500w of electrical power and 7.5 kw (26k btu/h) of
heat, and might last about 12k hours, with a $100 ring job at 6,000 hours.
>>that's seems a little too warm.
yes, although that temperature might occur naturally, and the generator
might be designed to operate at that temperature.
the motor and generator might be equally happy operating in free air,
or operating inside a basically unventilated insulated box containing
some thermal mass with a fan blowing warmer air over the motor and
generator, with no derating, if the "case temperatures" were the same...
we might measure the temperature of the cylinder fins and the generator case
under full load in free air (these are both likely to be warmer than 120 f,
but cooler than their interiors, since they both dissipate power), and turn
on an internal cooling fan in the box to blow warm air over the fins and the
generator as required, using a cooling thermostat (or two in parallel) set
to one of the measured free air temperatures and attached to the fins or
the generator case.