PSU Trouble

[kurt-olsson]

My converted PC PSU is starting to act wierd.

My rocket switch in the back is on and i have connected the green+ground together all time.

It has always started when i switch the powersupply switch on. But since yesterday it starts and everything is fine but i cant start it the second time without resetting or disconnecting the load.

If i wait for a night then start it again it will start with no problem.

I measured the voltage under load and it reads 4.3V and not 5.0V.
The 12V is 12V under load.

I think i need and extra PSU for my 5V and split the load.

How many Amps on 5V are you having on your PSU for backlight?
Anyone had this issue?

I have 15Amps on 5V. Maybe thats too much and it goes into overload protection?

[ame]

There should be a label on the PSU stating how much current you can draw from each voltage rail. Or total power available per rail or for the whole PSU. 15A @ 5V is 75W, which doesn't sound a lot for the whole PSU, but might be a lot for the 5V rail.

If you are hitting the limit on 5V then you could run a 12V supply to some circuits and use a small dc-dc converter to convert 12V to 5V where you need it.

[kurt-olsson]

Thanks for your input.
If i remeber i think it reads 30Amps on 5V, but it depends on if the rails are seperated etc.

I will buy a dedicated 5V power supply and test with.
Feels more stable to have one psu for each voltage.

[jackpilot]

I may be wrong but:
1) 30A not enough for 5V OEM backlighting. I have 2 PSUs on my cockpit, 600W and 1200W.
2) the PSU switch is always on. and I installed a toggle switch on the "green-ground" circuit which is used to flip the backlighting ON or OFF.

My 2 cents

[sagrada737]

I agree with Jack...   Although the converted PC Power Supply seems to have its rating, notice that the % VDC is broken out in the PC Power Supply wiring harness.  Pulling 25 Amps through a single PC power supply connector is problematic.

A better solution may be to use a dedicated +5 VDC Power Supply, such as the MeanWell brand.  These are very compact, low cost, and easy to wire/connect using common terminal connections.  For my 737 Sim, I use a single +5 VDC 30 AMP MeanWell PS, which handles all the +5 VDC BackLighting.  I also use a converted PC Power Supply for +12 VDC and a few +5 VDC requirements, eg. FlightIllusion gauges, etc.

Keep the PC power supply for general use, and add a high capacity MeanWell PS for BackLighting requirements.

Mike

[KyleH]

The symptoms you are describing are the supply going into a power limit mode that can only be reset by power cycling. You are probably at the edge, so the symptoms are showing up once there has been a thermal change.

Mike is correct. PC supplies are designed for computers. Use a dedicated supply for higher current applications like back lighting.
Don't go with 12V --> 5V. That reduces overall efficiency. Get a dedicated 5V supply.


(Former power supply designer)   

[kurt-olsson]

This forum rocks!

Thank you so much for all your help!
I felt that the PC PSU is not suitable for this application and will go for Mean well setup.

I am going to get help from a friend that is an electrician and he will help me build a box with 5V 30Amps, 12V 10Amps and 27V 10Amps (24V turned up) and make a nice casing etc. So i will have basically a custom power box for my simulator.

I just bought a 5V and 12V meanwell that will go first in this box.

Once again, thanks for all your help.

[sagrada737]

You mentioned placing multiple power supplies in a nice case...  We all want our Sims to look nice and well organized, but take seriously the need for your power supplies to have adequate ventilation.   As important, and as a safeguard, ensure that you have a good power Ground to these Power Supplies and that the Primary 120VAC connections are secure, properly insulated, and have proper fusing for the DC output.  In addition, you may want to fuse various sectors as used in your Sim.

Mike

[kurt-olsson]

I am actually thinking of building a wood box with proper ventilation with a fan, yet encapsulated so there is no risk of touching the hot wire.

Will add fuses for all my main modules about 10Amps.

The power supplys will have a solid connectoon to ground and wall socket is also grounded with a "ground fault" protector. (Dont know the correct english word for it)

[jackpilot]

A central power box will mean much longer wires from the box to the user modules.
My 2 cents is to place each of your PSU close to the specific user modules
Ex: I have two in the MIP, one in the pedestal, one (the big one!) close to the OVH, over the galley ceiling.

[kattz]

All of my power supplies are external to the sim, but they are HUGE.

[mickc]

Indeed.  My pedestal/TQ has 4 separate power supplies, and a modular fuse block that protects every item in the whole unit, and circuit breakers for each power supply rail. 
This fuse panel is accessible from a blank panel in the pedestal.

[KyleH]

I am actually thinking of building a wood box with proper ventilation with a fan, yet encapsulated so there is no risk of touching the hot wire.

Will add fuses for all my main modules about 10Amps.

The power supplys will have a solid connectoon to ground and wall socket is also grounded with a "ground fault" protector. (Dont know the correct english word for it)

Don't use a wood box if your using any sort of open chassis power supply It MUST be in a fire rated metal enclosure. Look up Hammond enclosures or something equivalent for stuff like this.
I'm assuming your in Europe and CE has different requirements, but here in North America, the only way you'd be able to use a wood enclosure is if the power supply is a UL Listed product (UL symbol), even then the manual may state otherwise. A UL Recognized supply (UR symbol) still needs to be installed paying attention to fire enclosure ratings etc.

[blueskydriver]

Hey Kurt,

You should look at getting two PowerOne units for both 5vdc and 24-28vdc.

Currently, I use the 24-28vdc model to power all my OEM 28v cockpit lights. It's in a metal enclosure and is very easy to interface with it.

You'll have to inline fuse your connections and have proper grounding for the metal enclosure; otherwise, it's simple and has no issues like PC PSU might have.

As a footnote, I used an OEM 28v relay to turn the power supply off/on with a standard switch. If you want I can post pics of mine.

Note: These are not my ads or anyone I know, they're just for reference:

https://www.ebay.com/c/673213543

https://www.ebay.com/p/661919803?iid=264259479394&_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D20170810094027%26meid%3D16fb90c7df8a42faa9c9a2e9283ab49d%26pid%3D100855%26rk%3D1%26rkt%3D1%26itm%3D264259479394%26pmt%3D1%26noa%3D0%26pg%3D2322090%26algv%3DSimplAMLSeedlessV2&_trksid=p2322090.c100855.m4779

Also, here is the 5v model:

https://www.amazon.com/Power-ONE-CP131-500-Supply-240V-AC-D609786/dp/B07CTFSLGS

https://www.amazon.com/Power-One-HCC512-AG-Power-Supply-100-264V/dp/B005T6GUOA

Happy Friday 13th,

John

[kurt-olsson]

Hi all! Thanks for the info John. They look like nice supplys.

I hade Murphys law issues! Hahah

My PC Powersupply could not handle all 15Amps. So it started to act wierd if not decreasing the load.

I then bought a Mean Well 50W 5V 10A power supply. I got help from my electrician and made an epic safe installtion.

BUT! It turns out that it can only deliver 8Amps at 230AC.

I am bummed about this because my MCP 3.3Amps and Pedestal 5.0Amps should be driven by that PsU. That was the plan from start.

I tested the PSU by removing panel by panel on my Overhead that is 12Amps 5V and at higher than 8Amps it goes into overload protection.

I will get a more powerful supply. A 90W 18Amp supply and test.

Nothing wrong with my PSU, i just overloaded it. And the protection worked.

[ame]

It could be inrush current.

Are the backlights LED or incandescent?

If they are incandescent then when you turn on the lamps they have a low resistance for a fraction of a second until they heat up. The low resistance causes a large current draw, which is called inrush current. The inrush current drops very quickly, but it might be big enough to trigger the current limit on the PSU.

Try connecting small sections of lighting until you hit 10A. For example, if you have five sections of 2A each then turn on the PSU with nothing connected and add each section. First 2A, then then another 2A and so on. The inrush current for a 2A load is smaller than the inrush current of the full 10A load, so it might not trigger the overload protection.

Also, check the data sheet for your model of power supply and make sure that the 10A rating is for continuous current.

Finally, the PC PSU should have been fine. You say it is rated at 30A for the 5V rail, and you were consuming 15A. It would be worthwhile trying to understand why it didn't work. If you don't know the reason then you can't know that changing the PSU is going to fix it.

Also, running 12V to a location and using a 5V dc-dc converter is a viable solution. Efficiency is not a consideration here.

[kurt-olsson]

Hi Ame and thanks for input.

I was dead wrong about 30Amps. It was only 20Amps and i think with everything connected i was pushing pretty exact 20Amps
12 Overhead
5 Pedestal
3 MCP

12+ 5 + 3 = 20 = Overload.

I feel stupid that i didnt doublecheck the amps on the psu. But i was so sure i had read 30Amps before i didnt bother to check.

I think your right about the precious statement.
Because if i used the internal boot cable on the PC PSU, sometimes it starts, but using on/off it was no-go.

I am ordering a 20Amps 5V. Even if i only get around 17-18Amps that will be fine.

Case closed i guess

[kurt-olsson]

Small update.

Everything working fine now. I am using a 18Amp 5V and drawing 16,5Amps in total for all my panels.