[original post is likely clipped to save bandwidth]
On 24 Mar 2007 00:39:18 -0700, "saleem"
wrote:

hi all,

I have a general question about the first what s KVA what actually it
is, second what s WATT and which one is the basic thing to know when
bying the generator /

thanks


There is a big difference between the two! To fully understand it, one
needs to understand imaginary versus real power. That is, understand
imaginary numbers. But the effect can be conveyed in less than
technically correct ways.

On many devices, Voltage an Amperage is not in phase. Motors, computers,
florescent lights.... That is peaks of each do not occur at the same
time. A crude diagram might be:



/\ /\ /
/ \ / \ /
\ / \ / Voltage
\/ \/

/\ /\ /
/ \ / \ / Amperage (note peaks at a different time)
/ \ / \ /
\/ \/

VA is simply multiplying the voltage magnitude times the amperage
magnitude. This makes sense for a generator since it outputs a certain
voltage and has a maximum current rating.

Actual wattage factors in the phase difference between the voltage and
amperage. It is the average of the instant power at any moment in time.
Since the Voltage and Amperage do not peak at the same time on many
loads, the wattage is less than VA.

Wattage represents real power, the power of the generator's energy. So
many HP can do just so much work. Thus for a given HP engine, the
generator is wattage limited.

The wiring is also amperage limited, usually higher than that of the
rated wattage of the generator. Thus a generator can output a higher VA
(wiring limited) than wattage (engine limited).

Hope this helps

gerry

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