[AMRadio] UTC CG-302

D. Chester k4kyv at charter.net
Thu Dec 6 14:10:22 EST 2007

> This auction is for an unused UTC plate transformer, Model CG-302. 
> Primary
> voltage is 105, 115, 210, 220, or 230 volts AC.  Secondary AC voltage is
> 950-750-0-750-950 volts; or you could also say either 1900 or 1500 volts 
> AC,
> center-tapped.  DC voltages and currents with suitable rectifiers are 760 
> or
> 610 volts in a full wave center-tapped configuration at 360 mA.  In a full
> wave bridge configuration there will be 1520 or 1220 volts at 250 mA. 
> These
> are continuous ratings and with a choke-input filter, I believe.  A
> capacitor-input filter will give you slightly higher voltages.  ICAS 
> current
> ratings will be higher.

I would be a little leery of using it in fullwave bridge configuration 
without knowing the insulation breakdown rating of the midtap.  Many 
transformers designed for the conventional two-diode full wave CT rectifier 
circuit have a midtap that is not insulated for HV, so the winding 
insulation to ground could break down, since the tap will be at 
approximately half the  high voltage potential with the full wave bridge. 
This can also be a problem when using a CT rectifier configuration with the 
filter choke in the negative side from midtap to ground.  The tap will be at 
a few volts DC potential, but the ripple voltage may peak at near the 
voltage output of the power supply.  The UTC catalogue or transformer spec 
sheet may or may not give this data.

Don k4kyv

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