Bridge rectifier using ultrafast diodes

[VK7ZL]

For series strings of diodes, I always base the number of diodes on being very conservative plus assume that one diode in the string has failed shorted, and so the N-1 number of diodes is still a conservative PIV; no propagation from a single diode failure.  You don't want to go overboard either, but diodes are cheap.

I'm for no parallel caps and resistors.  They just lower the MTBF of the diode string.  (We had to do that in the 1960's and this is 50 years later.) I don't think any high voltage power supply manufacturer today adds caps or resistors across the diodes.

By the way, is Australia 50 Hertz power?  (Even more time for regular diodes to switch.)

Tom
I will use 4 diodes and one capacitor per leg to be on the safe side.

VK has a 240V, 50Hz power grid. Freq is always correct, voltage regulation used to be 5% either side of centre but these days 10% is not unusual.

Fred
I decided against using MOT's due to the possibility of insulation break down as SB and others pointed out.

Bob

[W7TFO]

MTBF=Mean Time Between Failures.

Pretty mean, eh?

I mean it!

You're mean to me!

73DG

[KM1H]

Quote from: KM1H on October 18, 2011, 05:25:06 PM
There have been discussions on other forums by those in the industry showing documents stating they can even cause failures.

I remember that discussion. As unbelievable as this may seem, it sure seemed to be true. This may be the thread:

No, not that silly one which was fine until JI got involved.

Back when AMPS was a real active forum with several real engineers it was a topic that came up a few times and the people actually involved in the industry were members.
Those days died when the moderator protected JI when his make believe credibility was challenged and often proven wrong. The forum declined rapidly after that.