Electronics > Beginners

How To Connect Two PSUs, To Get More Current - Solved

(1/4) > >>

t1d:
In parallel, I would think. I need more current, to test an electronic load design.

Are there any safety concerns?

Precision of matching the voltages?

Floating grounds, etc? The DUT is floating.

Any tips are appreciated.

james_s:
What kind of power supplies?

Speaking generally, it's one of those things you can often get away with doing, but not something that is recommended. If you want to try it, just beware that you may damage one or more of the power supplies, or it may work just fine, can't say for sure without trying.

There are of course power supplies specifically designed for parallel load sharing, if 12V will do then most any hot swap server PSU has that capability and they are cheap as muck on the surplus market. They're quite powerful too, 600W-1kW is common.

Audioguru:
If they have voltage regulation then if one detects that the voltage is too high then it shuts down until the overloaded other regulator drops the voltage enough for this one to turn on. Then they might shuffle the load back and forth without increasing the current.

t1d:
Thank you, both, for your replies.

Doh, good question, James. I should have thought to include that information... They are both lab-type power supplies. Tenma and BK Precision...

They are just basic models... Meaning they can set either voltage or current to constant mode, but not both, at the same time. Both are Linear/transformer and 30v/3a.

As Audioguru says, for whichever is set to constant, the other is varied, to maintain the constant. For the test that I need to do, I do not want either to vary. The way I get that to happen is to set the current to constant, above the desired current level test point that I will drive the electronic load's current draw to. So, current and voltage are both maintained, unless I draw too much current, with the e-load, which I do not do, as I am watching the meters and the test level is below the constant current setting.

The problem is that PSUs say 30v/3a, but that is not simultaneously. The available wattage is the number of importance. I need more wattage, than I have available. That is why I am considering connecting them.

If I needed more voltage, I would just connect them in series. I know how to do that safely. But, I have never needed more current and, therefore, I have never connected them in parallel.

James, what kind of problems might come up? How can I avoid those problems?

Thanks, guys.

Mechatrommer:
if they are current limited psu, you can set both to exactly same voltage, connect them together and watch the current draw from each psu. if they can share load nicely, then you can do it. i think some precision psu is push pull type meaning when there is overvoltage, they will try to stabilize the voltage by pulling excess current to their ground, so two psu with different voltage setting, the one will try to keep up the voltage while the other will sink the current hard to the ground. but if stabilization is done only by a simple resistor, then it will be much less disaster. in case you want to be safe and/or the psu is not current limited type, no display to see current draw etc, put beef of schottky diodes rated for the intended current draw at each the psu output. say if you want to draw 20A from both psu combined, and you have bunch of 1A diodes stock, then try putting 10 diodes on each psu output, more is better for safety margin. ymmv.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod