PS to PS connection?

Ok,

I have this idea that two 24vdc power supplies with there vdc outputs connected in series well produce 48vdc output. Ok can it or not?

I need really to have a 110vdc 3Amp supply, but finding a transformer to handle 3amp at 110 or 120 vac is hard and expensive.

So I thought i could use 3 - 38vdc Adjustable PS connected in series to output at least 114vdc.

Let me know

Jonathon

As long as the outputs are fully floating!.

yes you can use powersupplies in series to get the required voltage value, but im not sure if your current requirement would be satisfied as the voltage would get added up in series but not current!

True as the current would have to be preset by each PS as to 3Amp each then the series voltage would add up to the total voltage required. Thanks for that information as I thought it would work.

Ok now for Nigel Goodwin's comment "As long as the outputs are fully floating!. " What does this mean exactly? So a +38vdc of one PS to the -38vdc of the next PS is not right?

Example:
+ (38vdc) - + (38vdc) - + (38vdc) -
+ ................(114vdc)............... -
The above is not correct? Then what do I need to do?

Thanks Jonathon

Fully floating means that none of the outputs of the power supplies are connected to earth ground or mains, even for the internal regulation circuitry. The manuals will tell you if this is the case ( no pun intended) or not.

zevon8 said:

Fully floating means that none of the outputs of the power supplies are connected to earth ground or mains, even for the internal regulation circuitry. The manuals will tell you if this is the case ( no pun intended) or not.

Click to expand...

Yes, if the negative of the ouputs is grounded, when you connect them in series you short out the lower PSU - often LAB PSU's can be connected as floating or not, usually via a metal link.

Good point Nigel, many have a removeable shorting bar at the front or something similar at the rear. These types will often have 2 "ground" terminals, one marked with a ( - ) symbol and the other an " earth " symbol.

Once I had a PSU that referenced the chassis in its protection/overload circuitry, and going to floating disabled that feature. The maker made this quite clear in the manual, and that it was due to requirements for global electrical standards.

So it's like a Logic Ground as it's not apart of the earth ground? Simply make sure the PS Grounding is isolated from the earth or any other ground in the combined PS's power output.

Ok thanks guys..

Jonathon