Computer room static blowing server power supplies

A raised floor server room with 6 servers, fiber optic patch panels, large control system cabinets and large UPS system, has been recently been plagued by computer power supply failures. The supplies fail when apparently many tens of thousands of volts jump from inside the PS around the switching regulators to the chassis of the supply taking out all the components. This has happened to 8 supplies so far. A visible blue flash has been witnessed several times by pewrsons in the room.

The servers so far affected are all sitting on the raised computer center floor. What ususally happens seems to be when a person enters the 12x20ft room or gets near a server a large snap is heard and the server is on the backup redundant PS, if it has not already failed.

We have been adding grounding bonding from all computer case to the bldg steel, raised floor structure, etc to try to stop this. Its still happening. The computers are various brands and varoious ages, from 1 week old to 5 years old. The probelm began occuring 2 months ago. The data center was built 12 years ago.

We are at a loss to figure out how the charge is building up on the inside of the power supplies. I am thinking about the common power source, via the power cords Hot, Neutral and Ground conductor.

The green wire should be bonded to the PC case. Apparently the PS regulator board floats above chassis potential. Apparently a large potential differnce is building. It jumps a 1 inch gap to the chassis. Burn marks from repeated arc overs are evindent (the arc that makes it fail is not the 1st time it occurs!)

The Hot and Nuetral..how could a charge be coming in on these conductors and getting past the MOVs to build a potential on the boards.

Any ideas would be appreciated. TJS

Reply to
T
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It sounds like your UPS's should take care of everything. I woulds have the UPS's checked out. I would have building electricians check things out. I would have installed whole circuit transient protection at the breaker box feeding the room.

greg

Reply to
GregS

I have had this problem before. The servers on site were blowing power supplies intermittently and corrupting the data on the HDD. After lots of parts swaps, softeware rebuilds etc the situation was getting extremely serious. I was called in to investigate. The site had a large UPS installed. Measuring the voltage with my digital meter I found the supply varying from approx 198v to 224v over a period of 1 hour. The UPS was isolated but the readings were very similar. I temporarily installed a mains analyser and when I returned a few days later, after looking at the printout was amazed to find that the power was fluctuating between 210v ~ 380v. It should be 220v.

I had a qualified electrician check out the site but he could find no fault. I then called out the electricity board who discovered an intermittent open circuit earth in the buildings 3 phase 415v power supply.

This was traced to a connection outside the building underground. After repair we had no more problems.

Reply to
Eric H

Put a humidifier inside the room, the air is too dry and static electricity builds up.

--
ciao Ban
Apricale, Italy
Reply to
Ban

BOLLOCKS! Load of crap. Some static charge that must be to crack over with a blue flash. Come on now!

Reply to
Eric H

Good info, (you must be in europe, 220v!) I will test the UPS circuitry. I think I need to find a 'sensor' to detect the charge build up on the boards. Somehow if the supply voltage is not the nominal 120vac and is instead

180vac or so, somehow the regulators are developing tremendous voltages on the circuit board to jump those gaps.
Reply to
T

"T" schreef in bericht news:Y-2dnR409fOTR6_ZnZ2dnUVZ snipped-for-privacy@adelphia.com...

Is ground still connected to good old earth? You'll have to check to be sure. Suppose the metal of the floor and installation has been grounded carefully but you'll have to check this too. An open ground connection may be the cause of you problems. Especially an open connection that is closed again by someone entering the room.

On all PCs and servers I know, the secondary of the power supply has been connected to the enclosure which in turn is grounded. So I assume the spark jumps from the primary of the power supply the the chassis. Looks like neutral and hot are floating which means that the neutral has not been connected to ground, at least not properly. (Don't know where neutral should be grounded in your place.)

There are other possibillities. Did someone install a badly insulated neon sign near you? Some other renovation maybe? Something else I can't even imagine but not very likely. I'm pretty sure something is not grounded properly anymore, but what?

petrus bitbyter

Reply to
petrus bitbyter

I don't think you need a sensor. That blue flash is good enough. Perhaps the exact point is no known. Regardless, monitor the voltage feeding the supplies, and the UPS input, and the voltages between ground and neutral. greg

Reply to
GregS

Then hire a mains analyser for a few days to monitor the supply. I presume you have 3 phase supplies going into the building as we do in the UK. your problem appears to be a mains supply problem.

Reply to
Eric H

T wrote: [...]

[...]

A near identical situation was cured simply by spraying the carpet tiles in the computer room and access corridor, with anti static solution. john

Reply to
john

My technicians have been testing the grounds to the steel and they are intact. We have a new fiber pull coming into the room just today via and existing conduit. The failures have been occuring for almost 2 months but much more frequently these last 2 weeks.

Reply to
T

I would have the electrical system inspected. The power transformer for the building may not be properly grounded. The ground rod or wiring may be damaged, leaving the transformer floating above ground.

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Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
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Reply to
Michael A. Terrell

An update; We are investigating "zinc whiskers" phenomina as a possible cause. The zinc filaments are produced from the plywood core floor panels supported by the zinc electrocoted support structure. When floor panels are lifted or disturbed the conductive dust can get into the power supply and lead to shorts between the modern closely spaced SMT devices. See here for a white paper

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The failures/arcs in our supplies have all arced from the 120vac chopper regulator collector to the PS case. If the zinc whisker problem is our case then the blue flash is just a 120/170p-p vac arc to ground, and not a static discharge.

We are looking at replacing our floor tiles with the modern ultra low static floor tiles.

I'm a little skeptical that this is the problem, but it is true that 2 months ago we pulled floor tiles to look for fiber conduits and that about the time the problems began

TJS

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Reply to
TJS

Reply to
Bennett Price

On Wed, 05 Apr 2006 12:59:59 GMT, "TJS" put finger to keyboard and composed:

What are the chances of zinc whiskers causing *exactly* the same fault in *8* PSUs?

- Franc Zabkar

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Reply to
Franc Zabkar

I'm skeptical about zinc whiskers and the white paper does come from a cleaning service company, enough said. But still it is a consideration

Reply to
T

AC is from overhead

Reply to
T

On Wed, 5 Apr 2006 22:05:11 -0400, "T" put finger to keyboard and composed:

I wonder why the arc jumps a 1" gap between the chopper and the chassis. Why not the much smaller (?) gap on the underside of the PCB?

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

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