Experimental Physics and
Industrial Control System

In the incident Tim describes, a faulty motor/drive connection led to the
motor driver heating up.  This particular drive was not fault tolerant, in
the sense that it did not have the capability to shut down when overheated.
Overheating led to the insulation on a toroid melting, and as a result, 48V
was connected directly to the  limit line(s).  As Tim mentions, these limit
lines are directly connected to the OMS VME58 board's PAL, via the P2
connector.  The connector, transition electronics, VME58 board traces,
and PAL were all damaged.  The backplane survived and is still in use.

Although we have had several other issues with the MAXv, to my knowledge
we have not seen the problem Ian describes, yet.

The most plausible cause I can think of is a short in or across the motor connector that put motor-drive voltage (~48V in our case) on a limit-switch line, perhaps only momentarily. I don't know about the MAXv, but the VME58 has limit-switch lines going straight to a PAL, which would certainly get crispy under this kind of assault.

We had an OMS VME58 (I think) burn up several years ago (eight, maybe?). I think Kurt
Goetze has the best handle on what happened, and he's out for a couple of weeks. I talked to
one of the staff at the beamline where the incident occurred, but I didn't get a sense that they knew exactly what led up to the incident.

Gillingham, IJ (Ian) wrote:

On the night of 30th December 2007, a fire broke out in one of our control system's VME crates. Considerable damage was inflicted on the crate, but fortunately the fire did not spread. On examination of the crate and VME cards, the P1 connector, to which a "MAXv 8000" card was connected, had been destroyed by heat/flame. Electrical burning of some components was evident on the MAXv card, these components were well away from the direct heat of the main area of combustion (components close to the fire were of course destroyed).

We are presently trying to ascertain which component caused the failure (the MAXv card, P1 connector or VME backplane).

Has anyone else experienced this type of event, in particular with the MAXv motor control card?

Ian Gillingham
Diamond Light Source

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References:

VME Toaster - has anyone else experienced this? Gillingham, IJ (Ian)

Re: VME Toaster - has anyone else experienced this? Tim Mooney

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