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homebuilt welding rectifier: single diode instead of bridge rectifier?

G'day,

Recently I've been given a defect welding inverter for parts.

While stripping it, I noticed the low-voltage rectifier (an inverter is basically a switchmode PSU, a grizzly-computer PSU) that rectifies the low-voltage AC to DC before exiting the machine. It consists of 3 diodes of 100A/600V each (RURU10060, for anyone interested).

The question: could I use this for rectifying the output of an AC-welder (transformer type) to DC? Or should I use full-bridge rectification for that (the 3 diodes in the inverter were wired as one bigger diode; as normal in switchmode PSU's). Commercial rectifiers for welders that I've seen all use full-wave rectification, which makes me doubt if my 'grizzly-diode' would work satisfactorily.

Hope anyone with an electronics+welding background can help here...

Grtz,

Peter Dingemans, The Netherlands.

Reply to
peter_dingemans
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Are you interested in selling parts of your inverter? Can you say what inverter it is?

i
Reply to
Ignoramus20247

By the way, regarding your question, rectifier bridges cost very little on ebay. You can buy a fully working one for afew dozen bucks, rated for 375A. Try searching for "semikron bridge".

i
Reply to
Ignoramus20247

AC welders need to be used with AC rods. The reason is that the current reverses and the arc may tend to extinguish while the current is zero.

If you only use one diode to rectify AC, there will be a much longer time that the current does not flow and the welder will not work as well as it does as an AC welder.

Dan

Reply to
dcaster

Using a single diode will cause DC to pass through the welding transformer secondary winding. This will cause the core to saturate. This will cause the fuse to blow.

Mark Rand RTFM

Reply to
Mark Rand

How d'ya figure?

Kevin Gallimore

Reply to
axolotl

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