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Re: Question about x-formers and spark gaps?



Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Andrew,

I'll take the KVA part ;-)

KVA is commonly used as a "power rating" for electrical equipment.  "Watts"
works for resistors and things that are not inductive or capacitive.
However, motors and things that have poor "power factors" draw current and
voltage out of phase.  Look at the voltage, current, and "real" power my
sync gap motor draws:

http://hot-streamer-dot-com/temp/4thHPsync.gif

Note that the "real power" is only 158 watts.  But the motor is drawing
114VAC at 4.36 amps!

It would normally be rated in "VA" which would be 114 x 4.36 = 497VA (0.497kVA)

The reason they use VA is suppose your wanted to wire this motor up and
wondered what kind of fuse and wire you needed for it.  If one just uses
"Watts" you get 114 volts at about 1.4 amps which is very wrong!  You
really need fuses and wire rated for 4.36 amps...  This is why big
transformers and such are rated in "VA" instead of watts because they are
assuming the power factor may be bad.  Rest assured that the power folks
learned all this "the hard way" :-))

kVA is just 1000VA.  BIG trannys are rated in MVA = 1000000VA

Hope this helps...

Cheers,

	Terry



At 07:38 AM 8/6/2001 +0800, you wrote:
>What is a MOV? What is the difference between KV and KVA and what does KVA 
>stand for? If I have a rsg with 4 stationary electrods, eight on the disc, 
>and a 1350 rpm motor, is my bpm to low. Help me please!
>
>Thanks, Andrew 
>-- 
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