----- Original Message -----

From: Peter Voelpel

To: ham_amplifiers@...

Sent: Wednesday, October 04, 2006 10:29 PM

Subject: RE: [ham_amplifiers] Re: 3 - phase HV supply

Sorry,

Power in a 3-phase supply is:

P=sqrt3*U*I*cos phi
P=1,73*400*35=24220

Indeed, for 25KW out one needs 45KVA, but only in class B.
67% efficiency is a bit high in class AB, it will be around 63% minus loss
in the pi-network.
Some of the output in a GG amp is coming from the driver, so efficiency is
NOT= output*100%/input power...

73
Peter

________________________________

From: ham_amplifiers@yahoogroups.com [mailto:ham_amplifiers@yahoogroups.com]
On Behalf Of pentalab

--- In ham_amplifiers@yahoogroups.com
amplifiers%40yahoogroups.com> , "Peter Voelpel"
wrote:
>
> Hi Dick,
>
> 3x35A is a 230/400V 25KW inlet.
> For 40KW 63A fuses are to be installed, mine are 80A

### whoa. 35 A x 400 V = 14 kw per phase. x 3 phases = 42
kva.

### To get 25 kw out [assuming 67 % eff on the lower bands]
25,000/ .67 = 37,323 watts of DC input. = 37.323 x 1.21 = 45.149
Kva.