Re: Convert Voltage/Hertz to Watts?

> Can Running Watts be determined with this information?

Hi Andy!  Yes.  But ignore the frequency.   To estimate the
wattage, just multiply the volts times the amperes.   However, 
note that this is a *peak* wattage, not the running wattage.
It's the max wattage expected to be drawn by a stalled motor 
during startup.  For example, 4.3A x 115v = 495w.   A freezer 
doesn't really need 500 watts or 4.3amps continuous, but it 
might draw that much if the back-pressure on the compressor 
is still high, (for example if you unplug the power while 
it's running, then plug it back in a few seconds later.)

Also be careful about the ratings of AC induction motors like 
those in refrigerators, freezers, etc. The amperes required 
by an AC induction motor are always higher than you'd predict 
from knowing the horsepower or total mechanical wattage
delivered.  It's best to actually measure the volts and
amps in the cable of the functioning appliance.

AC induction motors are very odd devices.  They came from 
the odd brain of Nikola Tesla, and their wattage requirements 
depend on the *phase* between the voltage and the current.  
An induction motor might draw constant amperage regardless 
of whether it's creating zero mechanical watts or 200 watts.  
In other words, a free-spinning frictionless AC motor could 
even draw 4.3 amps at 115 volts, yet draw zero watts from 
the generator!  Free-spinning AC motors are like inductors 
and capacitors: ideally they draw an out-of-phase current 
which consumes no energy.  (When you multiply the AC voltage 
sine wave times the AC current sine wave, you find that 
the energy sloshes back and forth between the AC power 
supply and the motor, and none is consumed.)   Because 
of these issues, it's best to measure the actual current, 
or even better to talk to the manufacturer of your 
generator or invertor, to see if they're rated for 
operating AC induction motors.




PS
Your motor plate also gives the Horsepower for the freezer
(1/4 Hp) and we know that 1.0 Hp equals 746 Watts.  A quarter-
horsepower motor is a 187w motor.  This is the motor's 
mechanical wattage rating.  That's lots less than 495w
electrical wattage!  And if the freezer doesn't use an
entire quarter-horsepower, the actual electrical wattage 
following startup will be lower.