"Robert Swinney" wrote in message
...
The formula as given is for the full load rated current of a 3 phase
motor, either delta or wye;
makes no difference. If one were to actually mesasure the KVA in each leg
it would be 1/3 the KVA
as calculated for full load. The math works with all 3-phase.

Bob Swinney

KVA is not current, and the formula is not for current. Full load current is
not equal to 3x that of current in each leg.


"ATP*" wrote in message
...

"Robert Swinney" wrote in message
...
Yes, but !! Be careful in caculating VA from current measured with a
clamp-on type of ammeter,
though. In as much as E and I are out of phase, any leg current measured
with clamp-ons will not be
accurate. Full load current will be equal to 3 x that of current in each
leg. The formula is:

3-phase KVA = (Volts x Amps x Sq. root of 3) / (1000)

In the formula above, Amps would be the circuit current. Full load current
(as in FLA) is the same as the current on one leg, if we're talking about
the same thing. The only way you can triple the amps in this case is if
you
multiply by 120, which makes sense with 208 wye since it could be
supplying
three 120 V circuits with a neutral. That math, however, doesn't work with
other three phase voltages.

Bob Swinney
"dan" wrote in message
...
When figuring watts or VA on a three phase circuit, do you triple the
amps measured on one leg?

Thanks.
--

Dan H.