RPS
Basics
What
is an RPS?
RPS
stands for Rack Protection System. Each VME rack has one, as does the DAQ
rack. Its job is to cut power to the
rack in event of a problem such as fire, over voltage, or lack of cooling air
flow.
The
1U tall black module at the top front of the rack is the RPS. The 3U black module in the lower back of the
rack is the AC Relay Box. The RPS has
many sense wires monitoring things in the rack, see the online documentation
for details of what gets watched and how.
There
are 5 buttons and 3 lights on the front panel.
Buttons,
from left:
1.
Smoke
Detector Reset
2.
VAC
Reset
3.
Output
Latch Reset
4.
Clear
Display
5.
Alarm
Silence (to the right of the lights)
Lights,
from left:
1.
Red
ALARM light
2.
Yellow
WARNING light
3.
Green
OK light
Meaning
of Lights:
If
Green light is on, things are currently OK.
If
Green light is out, things are currently NOT OK.
If
Red or Yellow lights are on, there has been an ALARM or WARNING since the last
time someone cleared the display.
(so you could have all three on at once – it’s ok
now, there used to be problems, but things haven’t been cleared)
ALARMS
are things bad enough to cut the power (like a smoke alarm). WARNINGS are things we should know about but
which won’t hurt the electronics (yet) such as DC voltages too low.
What
the Buttons Do:
1.
Smoke
Detector Reset
·
Resets
the smoke detector if there was a real smoke alarm.
·
Triggers
a test smoke alarm if things are ok.
Useful to force an alarm to cut the power.
2.
VAC
Reset
·
Push
this button to force the RPS to allow AC power to pass.
·
Hold
it down to start a rack that’s been off.
This allows things like the fans time to get revved up in order to make
the RPS happy so it will let the power stay on by itself.
3.
Output
Latch Reset
·
Clears
the RPS’ internal memory of past problems.
If this is not pressed after problems are resolved, the computer will
think there’s still a problem.
4.
Clear
Display
·
Clears
the display. Useful to get rid of old
lights. If there’s still a problem,
they’ll come right back on.
·
Does
not clear the computer readout of an old problem.
5.
Alarm
Silence
·
Shuts
up the annoying buzzer. Does nothing
else. For Temporary Sanity Saving
only. The silence is undone the next
time you hit “Output Latch Reset”
AC
Relay Box Buttons, Lights, and Switches:
The
AC relay box in the back takes power from the wall, a 208V/20A circuit and a
120V/20A circuit. Everything else in
the rack plugs into this box (except the RPS itself, which plugs into wall
120V).
There
is an overall “DC Control” light. If this
middle light is green, the RPS is telling the relay box to please let power
pass.
Each
of the two circuits has a 20A breaker (on this relay box as well as on the
wall!) and two lights. The “Input”
light is lit if that circuit is plugged into the wall and receiving power. The “Output” light is lit if the power is
being passed to the sockets on the back of the relay box.
Procedure
to power down a rack:
NOTE: if there’s going to be a power outage or if it looks like it’s going to last a while, please gracefully shut down the racks and cut their power at the main breaker box, to avoid power flickers!
1.
Make
sure there’s not a run going on involving this chunk of electronics.
2.
Press
the “Smoke Detector Reset” button. This
forces an ALARM condition and cuts power to the rack.
3.
Power
is now off. Consider turning off the
breakers on the relay box and unplugging the relay box from the wall for safety
if you’ll be messing with power wiring.
4.
Note
that the RPS is still on at this point!
That’s a good thing in general, but consider also unplugging the RPS if:
a.
You
will plug or unplug any sensors into the RPS.
Fuses can blow if you plug or unplug sensors while the RPS is powered up
(little green picco fuses inside the RPS chassis).
b.
Wall
power will be going up and down in a bad way.
Easier to shut things down at the main wall breaker box though.
NOTE:
If all you want to do is to work on the VME crate or FE electronics, you can
turn the WEINER power supply and/or the Harvard PDB off without powering down
the rack. The RPS will sound and there
will be a yellow WARNING. But, WARNINGs
don’t shut the power to the rest of the rack, keeping more things happy.
Procedure
to power up a rack:
NOTE: if power comes back up all over, say after a power outage, then some racks will power up on their own and others won’t. This is because some racks can get all the way back up in the few seconds power-on grace period the RPS gives. Others won’t, especially if the RPS has remained powered and warmed up. So, many racks might get to step 5 or 6 all on their own. Saves you button pushing.
1.
Make
sure things are safely plugged in and ready to get AC power.
2.
Check
that the AC relay box is plugged into the wall on both circuits, and that the
relay box breakers are “On”
3.
Make
sure the RPS is plugged in at the wall
·
A
newly plugged in RPS will scream, as the stuff it’s monitoring won’t be happy
because it will be off!
4.
Hold
down the “VAC Reset” button till the green “OK” light comes on. This might take the better part of a minute
– worry if it takes more than a minute, and go see what the problem might be.
5.
Sometimes,
the WEINER power supply does not come on when power is applied. They are supposed to do so, but sometimes
forget. In this case, flip the little
red front panel power switch up while applying AC power, and you should see it
start to boot.
6.
Once
the green “OK” light is on, reset the readout and display:
a.
Hit
the “Output Latch Reset” button
b.
Hit
the “Clear Display” button
7.
At
this point, only the green light should be on and everything in the rack will
be humming along.
The
first place to look is the DCS status webpage.
This shows all problems with the DCS subsystems and decodes the current
RPS status if there is a problem (login as numi, standard password):
http://minos-crl.minos-soudan.org/webdcs/dcs_status.html
The
iFix map of MINOS on the DCS windows machine in the control room will be back
up eventually. Problem areas flash on a
map of MINOS and can be clicked on to find out more and/or control things.
Lastly,
take a look at the /home/minos/rps/rpsdaemon.log file on the dcsdcp linux
machine. This file is a running text
dump of RPS problems. If you see many
problems on the status page, you can page through this text file and see what
problem might have started things shutting down – once power to the rack is
off, you of course have many problems all at once!
Documents
online go into gory detail about most of this stuff if you need more
information. Look at the UMD MINOS
homepage (the home page for the browsers on the DCS Windows machine in the
control room) and click on Docs, or go to it directly:
http://neutrino.d.umn.edu/~numi/docs.html
People
to Call with Problems or Questions:
Alec
Habig, 218-726-7214 (UMD) 218-724-9158 (home), ahabig@umn.edu
Jason
Koskinen, 218-726-8395 (UMD Lab), koskinen@alum.rpi.edu
Brian
Bock is also in that lab and might be able to help.