Perkins Climate Control System (PCCS)
Overview
The PCCS controls cooling of the Perkins primary mirror tub via a closed-loop chilled glycol loop to a chiller, radiators (heat exchangers) in the mirror tub, and fans that circulate air across and through the radiators to try to reduce the primary mirror temperature. The PCCSConsole (the GUI) also provides graphical summaries of temperatures, relative humidity, seeing, and predictions from the National Weather Service (NWS). This GUI also allows the user to start and stop the chiller heat exchanger fans, the circulating glycol, to set the temperature goal for the primary mirror tub, and to set a turn-off time for the chiller system (normally a couple of hours prior to the beginning of observing). The PCCS is a coordinated system consisting of two computers ('pccs' and 'thermal'), one data logging computer ('DT80'), the chiller unit, and the sensors and fans.
The 'pccs' computer displays the 'pccs console' gui, which offers two displays: an 'Environment' display and a 'Control' display. The Environment display shows temperatures around the observatory, inside the mirror tub, and as predicted by the National Weather Service. The dew points and temperature differentials are monitored in order to warn and draw attention to undesirable and/or dangerous conditions.
The Control display permits the chiller and fans to be turned on or off (including turning off at a fixed daily time), the goal heat exchanger set point temperature to be set, and the time history of the temperatures to be followed.
In general, observers are expected to start the fans and glycol circulating system at the end of their observing night, if no storm is forecast.
Starting the fans, glycol, setting temperature setpoints and turn-off times
- On the "Interfaces" option on the top of the PCCSConsole, select "Control"
- Click the radio buttons to turn the fans on and the chiller on
- Put in a temperature set-point value in the set-point textbox window, hit Enter
- Click the button to send the set-point temperature to the chiller controller
- Enter an automatic end time in the textbox with the 'hh:mm' entry, then hit Enter
- Click the button to send the end time to the chiller control
- On the "Interfaces" option, select "Environment" to return to normal display of key environmental temperatures, humidities, and differential temperatures, as well as seeing from the seeing monitor.
Restarting the components of PCCS
The DT80 is in frozen mode if it does not sound like it is making a clicking noise every second.
- Sometimes, its display shows an error. If that is the case, hit the Enter key. This generally clears the error.
- If the DT80 data logger freezes, the best solution is to push the RESET button with a paper clip.
- The reset button is recessed in a hole located on the left side of the DT80 unit, between the ethernet and usb connectors (see Figure below).
- You may need to press the Enter key on the front panel after a hardware reset.
The DT80 does have an internal battery which may help it stayed powered during some power outages.
- Login to the Lowell network via VPN
- VNC into the PCCS computer
- Exit from the PCCSConsole GUI on PCCS computer
- ssh into thermal.lowell.edu - so
- ssh pccs@thermal.lowell.edu (usual obs72 password)
- Verify the PCCSController daemon is not running
pccs@thermal:
ps -ef | grep PCCS
pccs 14436 1 0 09:34 ? 00:00:00 /usr/local/bin/PCCSController
pccs 14538 14511 0 09:50 pts/1 00:00:00 grep --color=auto PCCS
in this case it was.
- Kill the PCCSController, if running
pccs@thermal:
kill -9 14436 (or the correct job number, as shown in the ps)
- Restart the PCCSController daemon on thermal
pccs@thermal:
/usr/local/bin/PCCSController
- If the PCCSController has not be running for a long time…. go away and do something else for at least 30min. This will allow the data to build up in the MySQL database to actually build the graphs.
- VNC into the PCCS computer and restart the PCCSConsole.
- If the PCCS computer has been without power or was rebooted, you may need to relaunch the vncserver
- Log into PCCS, then issue a "vncserver" statement from the command line. VNC should be back up
- Double click on the PCCSConsole icon at right
- On the "Interfaces" option on the top of the PCCSConsole, select "Control"
- Click the radio buttons to turn the fans on and the chiller on
- Put in a temperature set-point value in the set-point textbox window, hit Enter
- Click the button to send the set-point temperature to the chiller controller
- Enter an automatic end time in the textbox with the 'hh:mm' entry, then hit Enter
- Click the button to send the end time to the chiller control
- On the "Interfaces" option, select "Environment" to return to normal display of key environmental temperatures, humidities, and differential temperatures, as well as seeing from the seeing monitor.