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AX1600i overcurrent protection triggered hundreds of times


gpin87

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Hello guys, nothing damaged here but unluckly situation happened and I would like to know more on the inner design of the input section of this PSU.

I have two twin systems with connected *a lot* of hard drives, one uses and AX1500i and one an AX1600i. When I built those, i noticed they triggered the OCP at startup due to the high total startup current of hard drives on the 5V line. Considering those systems are online h24, I usually powered them on by staggering manually hard drives connection (2 times/year for maintenance). To avoid the eventuality of a mains voltage dip triggering the restart of the systems and thus setting up a bootloop of restart-ocp-restart I used for more than a year a doubly conversion online UPS. I never really liked this solution because it's not inherently safe and not really energy efficient due to the doubly conversion UPS.

After some time i converted all my array to segate drives, that allows settings for a slower, low current startup, thus not triggering the 5V OCP anymore and solving the problem

Long story short, yesterday a voltage dip on the grid happened and I found my beloved AX1600i in the restart-ocp-restart loop that I had been able to avoid for years.
The AX1500i did not experienced that. With a bit more testing i discovered that with the low current drive spinup settings the OCP of the AX1600i is still triggered but only when it's warmer, i.e not being powered on after few hours sitting off. I suppose the working point was to close to the OCP limit that few degrees in the temperature made the difference in the OCP triggering values.

Now my question: PSU looks still  perfectly working, but I would like to know better how the input section works and if hammering it with probably 200-300 restarts could have cooked or degraded the in-rush limiting circuit or relay or something.
Maybe considering the restart cycle was around 15 seconds main caps stay charged and the subsequent restarts had lower inrush currents?

Thank you for the info!




 

Edited by gpin87
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How many drives are we talking about? The HDD motors are 12v powered so it's surprising they would trigger a 1600W unit.

I don't know if the AXi has a mechanical device for OCP, but even for a relay a few hundred actuations are no big deal. I'd imagine they just stop requesting voltage and try again, to avoid the slow response of a relay.

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1 hour ago, LeDoyen said:

How many drives are we talking about? The HDD motors are 12v powered so it's surprising they would trigger a 1600W unit.

40 drives.
it's not the 12V that is triggered but the 5V line, that has "only" 30A rating. After startup they draw only 15 A avg on the 5V rail, but at startup only they peak over the OCP limit.
 

1 hour ago, LeDoyen said:

I don't know if the AXi has a mechanical device for OCP, but even for a relay a few hundred actuations are no big deal.

uhm, when it's triggered I hear the relay clicking and the entire system just instantly shut off, waits like 5 seconds and then automatically tries to power on again.

Regarding the relay actuations, they are not a big deal when closing, because there is the soft start circuit (i wonder if that can overheat in my specific situation).
Openings under load are indeed stressful, unless it's and hybrid relay or something, hence my curiosity.

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phew ^^that's a lot of spinning rust..

I'm thinking if you use HBA / expanders cards for all these drives they usually have staggered spin-up options to avoid starting all the drives at once. I have an old LSI 2308 in my NAS with onlly 6 drives but i hear them start one after the other when i power it on.

If you're on PCIE sata cards, then i guess you'd have to lower the 5V load, maybe get rid of any RGB you may have going on, as few USB peripherals as possible etc..

Edited by LeDoyen
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17 minutes ago, LeDoyen said:

I'm thinking if you use HBA / expanders cards for all these drives they usually have staggered spin-up options to avoid starting all the drives at once. I have an old LSI 2308 in my NAS with onlly 6 drives but i hear them start one after the other when i power it on.

Thank you, I always wondered how those 108 drives jbod power up without tripping protections and that's the answer.

As the solution, I used the AX1600i in that system only because I had it around doing nothing  (bought it because i'm a nerdy tech geek and that was the coolest psu ever) but I had already planned to swap it for a psu with way more permissive OCP protection and put the AX1600i in my main workstation

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