DIYbanter - View Single Post - Computer room static blowing server power supplies

Is the air conditioning overhead supply or raised floor supply?

TJS wrote:
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 http://www.dataclean.com/pdf/zincwhiskers3.pdf

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

"T" wrote in message
...
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