Redundant 5VDC power supplies


#1

Has anyone ever had the need to have redundant 5VDC power for an Opto Rack? I’ve used QUINT DIODES from Phoenix Contact on 24VDC supplies, but I need to locate something for 5VDC.

Are Opto 5VDC supplies capable of being paralleled without diodes? Not sure what the failure modes would be if one of the supplies failed.

Any help would be appreciated.


#2

Couldn’t you just use the fault/fail relay contact that is built into some supplies? Or I think ABB makes some that can be hooked up parallel as a slave/master setup.
I’ve never really thought about a PS failure. They are cheap enough that I just stock one on the shelf here and it’s a max 5 min. swap if it ever happened.
In your current setup, how do you know if one fails?


#3

I have never had a SNAP PS5U fail in the shorted mode, which is what might cause the most problems.
I have had one fail open out of 100’s installed.
I haven’t seen a schematic of the Opto 22 PS though so not sure if there might be other issues. We have used both 5 & 24vdc in parallel without issues. If you use diodes you may want to use a remote sensing supply because of how picky 5vdc PAC’s are about low voltages (I know you know that, but in case someone else reads this,)


#4

I agree that the Opto power supplies are rock solid, I have never actually seen one bad…
I can tell you they are somewhat special in that they are a switching power supply and then also have a linear transistor output section, which is why they are super quiet and have excellent regulation.
The only other source I use is Meanwell Power supplies. You can get them at TRC Electronics. They have an outstanding quality and make a lot of different versions including the type that can be paralleled.
On the other hand, if you have 2 Opto supplies I am pretty sure it will not burn them if you set up a test to try it.


#5

They do seem to be good supplies, but they are not infallible. I’ve had two Opto 5VDC supplies die on me - one just stopped supplying power - fuse was good, the other lost voltage regulation and would cause some of the modules to read wonky. This is nothing compared to the failures from old 25 year old non-Opto open frame supplies (±15/5VDC) that are powering some old stalwart B2 controllers that we still service - we’ve been changing these out for some by Sola.

For my original request, we changed the design to not require an active standby power supply. This is for a CHW pumping application for a data center. We added a mechanical relay that will activate a fixed speed input on a couple of the drives if the relay drops out. This will give them some flow while a tech changes out the power supply, if it is ever needed.


#6

Yah, the ol’ Power One units were fairly bullet proof, the only issue with them versus the Opto supply is that the Power One units will drift over time, whereas I have never seen any drift on the Opto units. They come set accurately and stay that way until they fail.
Speaking of that, one of my customers is the outfit that makes the pipeline flash testers (which I migrated from LC4’s to R2’s) and they are still trying to get their customers off of the units with LC’2 and LC4’s…these units sit out in the desert heat inside an explosion proof enclosure (40+ bolts in cover) and run and run and run…


#7

Ha, I have a similar setup for our cold storage. Old open frame linear supplies for the B1/B2 boards. Beginning of this year we just did an upgrade to E1/E2, & Snap controllers and I ditched the linear 5v/24v supplies for ABB units. We were getting lots of power quality issues (spikes & dips) and the linear units would follow along causing bad things to happen. I have yet to find a ±15v switching supply large enough to replace that linear unit…


#8

We are using Sola SCP30T515-DN Has 3A on the 5V rail, and 0.5A on each of the 15V. One for each B2. Now let’s see if we can get 25 more years at of these…