To achieve 1,5% ripple from a 6-pulse power supply of 5KV at 3A you will
need a capacitor of 0,32?F.
Without any cap ripple will be 4%.
You will not here any hum from a transmitter without capacitor in the
6-pulse capacitor when using sideband transmissions.
From a carrier you here little hum on zerobeat.
The formula to find C for the 3-phase bridge circuit is the same as for any
other circuit, just calculate C from XC by using 300Hz in the formula.
How the transformer is connected does not matter, usually the primary will
be delta for best efficiency and the secondary will be star connected.
You will have 2 diodes per leg. The voltage across one winding is dc/sqrt6.
I my 7KV 4A CCS P/S I use UGE1112AY4 diodes by IXCYS, 3 per leg, just scewed
one into the next.
The transformer secondary is 5KV +/-5%, +/-10% phase to phase, or 2887V
across one winding.
I use 2?F 10KV for smoothing and a crowbar overload circuit with it.
73
Peter
________________________________
From: ham_amplifiers@... [mailto:ham_amplifiers@...]
On Behalf Of pentalab
Then, if we talk 3-phase supply and 6-puls rectifying,
lets say around 5 kV DC potential, how much glitch C
is needed to achieve 1.5 percent ripple?
### Dunno. You would only have 5% ripple with NO cap.... and
with a resonant choke set up.....you probably wouldn't need any
C at all ! [3 phase]
### IF no resonant choke setup... and just a straight C input
filter.... I'm guessing around 5-16 uf would be plenty. It
would also highly depend on the load.
### I haven't found any formulae for a C input filter HV
supply........ with 3 phase. I don't have access to 3 phase....
so never pursued it. It would be the ultimate setup. IF you
find anything... let me know... as I'm most interested. Somebody
is going to ask me to engineer one for em... so I had better
research it.
### I did see some info on C input 3 phase HV supplies some
where.... it's in Orr's older books.... but not alot of info.
Seems to me he had the 3 x primary's connected in a "Delta".....
and the 3 x secondary's tied in a.. "star". The rectifier set
up... if I remember, sorta looked like just 2 x diodes per sec
winding... one flipped around If I remember. The RMS voltage
per sec winding vs no load HVDC output is what threw me.
With say a 1 kv sec.... I'm positive... the OCV hv wasn't 1414
Vdc. [I may well be wrong with this.. just going by memory]
