HHO power supply question

[keiththevp]

OK, I have built a new power supply that can output 0-150v DC 25 amps from a variac and bridge rectifier on one side and can output 0-15v DC 120 amps from 3 transformers on the other side. I want both power supplies to output to the same positive and negative leads to load. I have installed relays to turn on/off the power to each side of the power supply. But I do not want the power from either source back feeding into the other source, so ....

How would I wire in the diodes and in what direction in order to stop current from passing from one power supply to the other and instead just going to the load? The best I could find are 40 amp diodes (since I could not find or afford a 120 amp one) so I will have 3 positive and 3 negative leads coming from the 3 transformers that will need diodes. I have attached a rough drawing of what I am trying to do.

Thank you for any help electric gurus!!!

Keith

[Philldpapill]

Put a bridge rectifier on the output of EACH transformer, then tie the outputs of the rectifiers together. You really should have diode capacity of at least 3 times the rated current that you want to use. In other words, each diode on the output of a transformer should be rated for 120A minimum. If you get on the ST.com site, they actually offer "free samples" of some beefy diodes. I have some rated for 200A. They are normally a $45 part, but.... well, I love free samples.

[keiththevp]

I already have 2 50 amp bridge rectifiers on each of the 3 transformers to turn them into dc. What I was wondering is if I had to put diodes on as well or will the bridge rectifiers stop the current from one supply going to the other?

[keiththevp]

Forgot to add that the bridge rectifiers only have a positive out the neg comes from the transformers.

[keiththevp]

Should I try to hook the negative up to the BR and remove from the transformer? Also here is a more detailed drawing of the current wiring config

[H2OPWR]

Should I try to hook the negative up to the BR and remove from the transformer? Also here is a more detailed drawing of the current wiring config

Keith, From your drawing it looks like you have the transformer output going through the variac. Is that the case or am I just looking at it wrong? If that is the case this set up will not work.

Larry