Power Outage (Unplanned) Stanford Notes
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EMERGENCY POWER OUTAGE PROCEDURES (and planned outages too). Last updated 12-1-2003 MWistey
I made an unfortunate discovery... You know the cart with the oscilloscope on it, which I've been using to debug the RHEED camera? I was pushing the cart gently out of the way as I walked around it, and it turns out that it's exactly the same height as the big, red emergency shutdown buttons on systems 4 & 5. ...Doh! Fortunately, it looks like there's no damage.
But it occurred to me afterward that we do need to make sure the new folks know what to do in case of a power outage. We've been pretty lucky this year and haven't had to deal with them. Here's my list, and I'm sure the other system gurus will have things to add.
BEFORE THE OUTAGE... see "openingchecklist.txt".
>>>>>>>>>> DURING THE OUTAGE <<<<<<<<<<< 1. Check the temperatures of indium and aluminum cells. They should be
on emergency backup power, but if that power were to go out for any
reason, the cells will freeze quickly and shatter their crucibles.
(Backup power is DC, so our clip-on ammeters won't show it even if
it's working. Use a DC voltmeter if you're worried.)Shut off gas flows: disilane (Sys2), N2 (Sys5), and CBr4 (Sys4). 3. Shut down Arsenide and Telluride. Not only will they be safe when
the power comes back on, but you might be able to use the battery
backup to keep aluminum hot for a few minutes longer, if the backup
power fails. You have to be logged in as root, and type "shutdown -g0".
It'll ask if you really want to shut down.Manually open the As valves several turns, so the needle valves don't
get stuck while the crackers cool. Turning clockwise into the
machine opens the valve (the opposite of most valves). If the valves
are already stuck, don't force them, just wait until they get reheated.Make sure the cryo gate valves are closed. 6. Close the vacuum valves on the liquid nitrogen diffusion pumps in the
back hallway to prevent oil backstreaming.After the outage... 1. Turn the power back on. You have to hit the little black "On" button
on the System 4 breaker box. Then do the same for System 5, which
gets its power from System 4. If it was a brief power outage (like
some fool bumping the Emergency Off button ;-) do this quickly and
you'll save yourself grief.Check the temperatures of aluminum and indium. **If they've frozen
solid, don't let them re-melt, or the cells may be destroyed.** Note
that the source material may still be molten even if the thermocouple
reads below melting temperature, because it takes some time to
freeze.Push the little red Reset button on the backup power supplies for
indium & aluminum: these are the big blue & white boxes in the
racks with just a fuse and a red pushbutton on the front, and maybe
a couple of adjustment screws.Check the temperatures of the remaining sources. The Eurotherms are
probably going berzerk after #1. You may need to set them to a small
amount of manual power until the temperature settles down. But
usually they'll be okay.Turn on the ion gauges. 6. Check the cryo pump temperatures. If they're okay, open the cryo gate
valves.Recalibrate the As valve controller. (Turn the System 4 arsenic valve
clockwise into the machine a couple of turns to open it, then hit
"No" when the controller asks if you want to calibrate it manually,
and "No" again for full valve travel. It will close the valve
automatically. Repeat for System 5.)Set the arsenic valve controller and CBr to Remote. 9. Watch for signs of leaks, both inside and outside the chamber. The
cooling water pipes have an unfortunate tendency to leak when the
temperature is cycled through them. But don't panic--it might just
be ice which has melted and is running out from the insulation.Check any other instruments which may need to be turned on, or which
may have lost their settings.Reopen the vacuum valves on the liquid nitrogen diffusion pumps in
the back hallway, if you closed them.