Can two power supplies be used on the same SS Hub?

[taybrynn]

I think I know the answer to this .... but I've got a fairly small power supply (like 30A max) and I'm finding very little use for it for my 2013 show, since most of my SS hubs will require more than that. 

Had anyone hooked up two power supplies to the same SS hub?   Like hooking up the main ATX connection with one and then the 4 smaller power plugs with the other?

Again, please explain to me why this is or is not a good idea.  I have a feeling its probably not a good idea ... but I'm not sure what to do with my 30A PS.  I;ve noticed a lot of 430w power supplies like it for very good prices (on sale) ... so if the two could be combined, it could be a cheap path to 60A potentially.

[Steve Gase]

Bad idea.  I'll let someone else explain the reasons why... but essentially you'd be tying two supplies together, and that would ruin one or both supplies.


If you want to separate the power delivery, there are smart string passive hubs that plug into the SS Active Hub and extend the signal -- but also give an opportunity to introduce a separate power supply used by the strings that connect to that passive hub.


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[chrisatpsu]

when you add a 2nd computer power supply, you're essentially adding a 2nd 12v rail.
the requirements for the hub is a single rail power supply.

[taybrynn]

Thanks ... thats all I needed to know.

I had been looking into the 4-port passive hubs and have a couple already.

I noticed Ray sells a 10A 12v power supply now for $14 ... I have some of the
smaller PS he sells and they all work fine.

[chrisatpsu]

i have 2 of his 10A 12v power supplies.  their especially handy for testing things.

[taybrynn]

I recall ordering a smaller 5A supply and since he was out, he sent me the 8A for the same price.

[rm357]

There are always small variations in power supplies and some are better than others at being paralleled.

If you get a couple that don't like being paralleled, even a difference of a tenth of a volt could result in the one with lower voltage looking like a low impedance load to the one with the higher voltage.

Even if they do work ok in parallel, the one with a slightly higher voltage will always be worked harder than the second one. The second one will only start help when the current through the first one becomes enough to drop the voltage to the level of the second one...

[JonB256]

If they are adjustable and the same model, you can "balance" them pretty easily. If you had two 350W supplies (like Ray Wu sells), you could easily connect them both. Put some load onto the Hub and then adjust their voltages to be the same.

If you have a way to measure the amps, that would be best, but volts are easier.

If the voltages won't stabilize, like they are slowly cycling the load back and forth, then abandon the idea. Depending on how they regulate their voltage output, they could oscillate and actually damage each other.

Then again, if they do oscillate when you set the voltages at the same value, then drop one by 0.1 or 0.2 volts so that it lags. That should stabilize them.

[chrisatpsu]

If you're a beginner, or average lights user, but not up on some of the technical stuff, connecting two power supplies is a bad idea.

If you're a little more savvy into electrical engineering, then this question is probably moot for you since you would have something different figured out in your head already.



A Optimist sees the glass as half full
A Pessimist sees the glass as half empty
An Engineer sees an improperly designed storage container
An Opportunist consumed the water while everyone else was debating

[n1ist]

It depends on the power supply; most do NOT like being paralleled, especially without equalizing diodes.  Too easy for one to take all the load until it smokes.

I worked on a project where we used 6 28V 100A supplies in parallel but they were chosen because they allowed that.  We really observed the "no rings, no conductive jewlery or watchbands" rule around them.

/mike