2 MeanWell SP-480-24 in parallel

Ypedal

Ypedal

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I'm setting up 2 mean well power supplies SP-480-24's in parallel, i powered each one up and adjusted the trim pots to 29.0 volts .. paralleled both as shown :

mwSP480-24.JPG

When powered up, the fans from each unit will go high then low rpm in a 2 second pulse..... this is with no load..

Is there anything that needs to be done to prevent this ? or will it all smoothen out once i hook up a charger ( my 3010B ) .. ?
 
Ok.. so i plugged in the charger and gave it a go, if i adjust a hair of a turn on one unit the fan stops on the other, i lower the trim and the fan stops on unit 1 and fan turns on unit 2..

but the problem is that the unit on stand-by ( not outputting any power but still in parallel with the other.. ) has it's fans bumping a few turns every few seconds... is this bad for the fans ?
 
I have mine connected exactly as you have Gaston, has been solid for the last 6 months using them most days, mine however max out at 27v unfortunately :-(

KiM
 
It's somewhat critical that you get the output voltage of the two supplies as close to exact as possible. The way you have them set up, the top one has lower voltage coming in, due to the additional losses in the short length of wire and the connection on the primary supply. Also, the top supply has additional resistance on the output, for the same reasons. One way to eliminate this as an issue is to run one wire on the top supply, and one on the bottom. Still leave the wires connecting them, but run the AC black wire to the top supply, and the white wire to the bottom. They both have essentially the same voltage, since they both have a similar current path. Do the same on the output, put the + wire on the top, and the - wire on the bottom.

Then you would want to trim the supplies as close to exactly the same as possible. If your charger is rated for the voltage, crank the POT's on both, and see what the voltage is. If one is slightly higher, lower it until they're identical.

That should get the supplies to share the power fairly evenly. Even a minor difference will make one take a lot more of the load, making the dual setup pointless.
 
Keep up posted. I just ordered 2 SP-320-24 units and will be watching what you do and mimic it. :)
 
Mmmm... I'd personally have 2 X 12V in series, getting them to current share evenly without combining resistors will be really difficult to do.

I think if you get them really close, then run the length of leads you want from each supply to your load (rather than the nice looking, but functionally difficult way they are set up now) then the resistance in the leads may help you out with current sharing.
 
If the power supply had voltage sensing would then being in parallel the individual power supplies would self adjust to the same? Maybe just nonsense but it's what my small knowledge is coming up as a solution.

*edit*
Just some googling has found the answer. So basically with remote sensing feature in the power supply hooking both in parallel can be simple and trouble free. Just no help with your current problem as you do no have that feature and neither will my soon to arrive PS. :(

built-in active current sharing function and can be connected in parallel to provide higher output power :
(1)Parallel operation is available by connecting the units shown as below.
(+S,-S and CS are connected mutually in parallel).
(2)Difference of output voltages among parallel units should be less than 2%.
(3)The total output current must not exceed the value determined by the following equation.
(output current at parallel operation) = (Rated current per unit) x (# of units) x (.9)
(4)In parallel operation 4 units is the maximum, please consult the manufacturer for applications of more connecting in parallel.
(5)The power supplies should be paralleled using short and large diameter wiring and then connected to the load.
 
What are you using for voltage adjustment? the standard pots or have you replaced them with multi turn pots.

I could nevr get my pair to balance nicely till I swapped the standard single turn pots with multi turn 5k pots, with multi turn you can really have accurate control of the voltages.
I connected a pair of ammeters to mine and adjusted the voltage by watching the ammeters, far more accurate than adjusting just via viewing the voltage alone. As as pointed out earlier, even if both output voltages are exactly the same, current may be different due to differences in wiring.

Also do the Q5 style fan mod, to keep the fans on permanently. That way you do not get the current fluctuations that happen when the fans kick in and out
 
With just a 10k pot installed. (It was on hand) Only #1 PS runs when just powering the charger but once I start charging a battery even at just 1A #2 turns on and they both share the load. I can't tell for certain until I can recharge my 15Ah pack at 15-20A to see if they are really running parallel or not. :) Thanks for posting the helpful info. Hope Ypedal can get his setup working.
 
When you say
When charging at battery, #2 turns on, how do you mean? Do you mean the fan comes on?
If they are both plugged in to the mains, unless you have some fancy load monitoring and relay to switch the mains on, then they are both already ON
 
I put the meanwells back on the shelf for the time being.. and switched to these :

http://endless-sphere.com/forums/viewtopic.php?f=14&t=32080&hilit=motorola

they are awsome, the fans dont come on while i charge 6A at 10 amps, i regularly do 15 and at this point they come on and off in 5 minute intervals...

the MW units are loud as hell, fans on full speed the moment they are turned on.. they will make a kick butt 48v charger shortly tho !!.
 
NeilP said:
When you say
When charging at battery, #2 turns on, how do you mean? Do you mean the fan comes on?
If they are both plugged in to the mains, unless you have some fancy load monitoring and relay to switch the mains on, then they are both already ON
Click to expand...

Opps, to be clear I mean the fans turning on. They are both powered from the same wires and both green leds are lite. So now charging my lipo in 6s6p setup it's charging 20A. Just took some patience and changing the pot. Hope those new PS you picked up work out for you Ypedal. :)
 
Ah well, jsut because the fans kick in a different times means nothing in relation to the load sharing really..OK a littl ebit of correlation I suppose, but it only takes for the temp sensing thermistor to be a fee mm further away from the heat source on one than the other and then fn is going to kick in at a different time.

A pair of ammeters is the answer. Even cheap $5 ones will do

First put each one on 10 amp range in series with each other and the PSU and load to compare the accuracy,

Then put one on parallel with each PSY output, and adjust your voltage to get equal current from each supply
 
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