is it possible to extend amperage headroom by running multiple power supplies parallel?

Hi,
i have 3 pieces of Meanwell RT65B in my rack and i am quiet happy with it.
the specs are

+12V 2,8A  
-12V 0,5A  
 +5V 5,0A

which is a bit poor on the -12V line.
now i am planning to build a bigger case 197HP x 18U where each of the 6 rows gets one RT65B
I do have a module (WMD Performance Mixer) which is very hungry (430mA) on the -12V line. so i do not have enough headroom for other modules within this row.
it would be possible to add a 2nd RT65B to this row for having one power supply per bus board. but even that is not enough headroom on the bus board the WMD mixer is connected to.

So my question:
is it possible to interconnect all busboards which have a separate power supply?
so my result is 6 pieces of RT65B all connected together in parallel on the secondary lines (-12V, +12V, +5V, GND) for extendig the headroom for all 3 voltages over the entire rack.
As far as i know the voltage won't change as long as it is connected parallel.
thanks for any advice!

maybe my question was hard to understand. so here is another approach:
is it possible to sum up the headroom of all PSU's for all voltages over the entire rack by simply connecting the bus boards with 16 pin flat cables like this (or alternatively on the stronger wires directly on the PSU's output terminals which is technically the same)?

thanks in advance for any feedback or thoughts!

EDITED Oct 12th 2022, 07:46

So, in theory you can do this, but in practice there are a lot of ways it can go wrong too. If the supplies aren't perfectly matched (far closer than normal usage would require, so they probably aren't) they won't share the loads evenly, so you won't get as much extra headroom as you'd think, and if they're very badly unmatched they might drive power directly from one supply into another. Also, depending on their design they may also develop resonance/interference between them leading to, at best, very unclean power, and at worst, equipment-damaging surges. You might get away with it, if you're lucky, but i doubt anyone on here will be willing to say you will get away with it. I certainly wouldn't encourage it.

EDITED Oct 12th 2022, 14:48

If I remember correctly some Meanwell type of converters allow parallel use. They have a kind of current sensing wire and compensation circuit. I believe there’s also an application note available on their website.

If I remember correctly some Meanwell type of converters allow parallel use. They have a kind of current sensing wire and compensation circuit. I believe there’s also an application note available on their website.
-- BrumoD

yeah, for proper load sharing they need a little bit of sensing, but some (not all!!) dumb supplies are designed for parallel usage too, just with less-perfect sharing. I just don't know if OP's particular one is or not and can't quickly tell from its datasheet (usually a bad sign).

thanks @justarandomgeek and @BrumoD for your answers!
I found the hint for 'current sharing' on the Meanwell website.
The RT65-B which i use, does not have this feature.

But in the Datasheet i found that there will be headroom up to 1A on the -12V line as long as the total power consumption does not exceed 64.4W

so instead of trying to connect the PSU's parallel i am going to add another RT65B in this specific row and everything should be fine...
thanks again!

please do NOT bridge your psu in parallel. when one gets broken your other lines will be overpowered and may burn down !
it is possible to bridge them for redundant use, but only until total power output for ONE psu.
datasheet RT-65B :
rated current : 5V=5A / +12V=2,8A / -12V=0,5A
current range : 5V=0-8A / +12V=0-3,5A / -12V=0-1A (Note 6: Each Output can work within current range. But total output power can't exceed rated output power.) here 64W, but try to stay below 80% i.e ca. 54W.
That means if you have 1A on the -12V rail you have max 2,3A on the +12V rail. so you can use your hungry WMD module within this rules. cheers.

so instead of trying to connect the PSU's parallel i am going to add another RT65B in this specific row and everything should be fine...
thanks again!

-- modular01

Yeah, just adding another "power zone" is definitely the easier/more reliable solution!