At 09:51 AM 02/03/2000 Rich Measures wrote:
> Don't most rectifiers conduct in half cycles?
That depends on the filtering network they are supplying. For a choke input
the answer is yes. But the answer for a capacitor bank input the answer is
not so clear.
The only time a diode conducts is when the output voltage of the rectifier
bank exceeds the voltage of the of the filtering network. After the
capacitor bank has been intially charged and reached a steady state the
conduct angle can be quite small. Factors determining this time include the
size of the capacitor bank, the internal resistance of the caps, the
bleeder resistance and the glitch resistor. A conduction angle of 20
degrees is not uncommon. The formulas presented by Steve Harrison acurately
determine the conduction current.
During intial charge up the conduction angle is a full 180 degrees at
switch closure which will eventually decay to the steady state value.
Most of us are well aware that a step-start circuit is needed inorder to
protect the rectifier string during start-up. We know that 30 cycles or 1/2
second is the appropriate delay factor. But how does one determine the
correct resisitance value to be inserted in series with the the primary of
the plate transformer?
Just another Diode Lover :) Give me an 866 with their purple glow
Bob K1TA
--
FAQ on WWW: http://www.contesting.com/ampsfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|