On Sat, 25 Mar 2006 03:07:30 GMT, Carl Byrns
wrote:

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

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




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?

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.

Yeah, these days you have to under rate the cheapos by a factor of 3
to 3.5 for induction motor starting; otherwise, the term,
"instantaneous field collapse" takes on a meaning they don't teach in
electrical engineering school -- you ain't seen nothing until you've
seen a cheapo decelerate from 3600 rpm to zero in three revolutions.
Just make sure you are not standing inline with the engine when the
crankshaft exits the crankcase or you might be shopping for a set of
dentures. The cheapos are built for resistive loads only.

In the interests of reducing shipping costs for the mass market,
they've reduced rotating mass on the cheapos to the point where it is
nonexistant and advertise it as making the gen set more "portable."
The surge current capacity on a cheapo is near zero.

When you are under rating a cheapo for induction motor starting, you
are not doing so for the purpose of buying more resistive Watts. You
are doing so for the purpose of buying more rotating mass for the
purpose of getting enough surge current capacity to start an induction
motor.