DIYbanter - View Single Post

On Fri, 24 Mar 2006 20:10:44 GMT, (Speechless)
wrote:

On Fri, 24 Mar 2006 03:01:13 -0600, Richard J Kinch
wrote:

When buying a gen set, you need to understand what you are going to do
with it, and then make sure it has the capacity to supply enough power
at the voltage you require to do the job. This means that you have to
read the detailed specifications for each power outlet on the gen set
that you will actually plug your load into, rather than relying on the
overall power rating the generator.

You have ONE power cord coming out of your power tool that you plug
into ONE power outlet on the generator supplying 120 Volts. How much
power can that ONE outlet deliver? How much power do you need from
that ONE outlet?

A 4000 Watt gen set supplying 2000 Watts per outlet from two outlets
is not going to do the job if you need to draw 4000 Watts from one
outlet. This is the difference between a "cheap" generator and an
"expensive" generator. The "expensive" generator can deliver 4000
Watts @ 120 Volts from one outlet. The "cheap" generator delivers
2000 Watts per outlet from 2 outlets.

If you are planning to run a motor off your gen set, your gen set must
be sized for the power required to start the motor, and not for the
power required after the motor is running. The rule-of-thumb is that
the generator power required to start a typical fractional horsepower
induction motor is about 10 times greater than the nameplate
horsepower rating of the motor converted into Watts. For example, 1/2
horsepower converted into Watts = 373 Watts. To start a 1/2 hp motor,
your generator must deliver 10 x 373 Watts = 3730 Watts FROM ONE
OUTLET. Can it?

Great answer- we used to sell gensets and customers would undersize
them because they didn't figure inrush current.
Our rule of thumb for motor starting was three times the running
amperage, with the power source a high quality genset. We didn't sell
cheapos.

-Carl (proud owner of a genuine Kohler Electric Plant)