There are usually five PID loops operating on the IOC.
Brief descriptions, along with typical PID parameters,
are given below.
1. EV9180
Liquid level LL91101 is used to control the
supply JT valve EV9180 so as to
maintain a constant liquid level in the buffer
dewar.
Input
LL91101
Max Pos
70.00
ST
240.00
Set Val
65.00
Min Pos
see below
Gp
2.000
Max Chg
2.00
Gi
0.003
Min Chg
0.50
Gd
0.000
2. EV9180A
Temperature diode TD9178 controls the minimum
position setting of the above PID loop for EV9180.
This ensures sufficient flow through buffer dewar to
keep the its plumbing cold. If the exhaust gas of the buffer
dewar warms much above 6 K, it can no longer be sent
to ESR's cold return line.
Input
TD9178
Max Pos
90.00
ST
240.00
Set Val
5.80
Min Pos
30.00
Gp
-10.000
Max Chg
2.00
Gi
-0.020
Min Chg
0.20
Gd
0.000
3. EV9178
Buffer dewar pressure PI91104 is used to control
the cold return valve EV9178 so as
to maintain a pressure in the buffer dewar sufficient
to transfer liquid from the buffer dewar to the magnet dewar
(about 1350 mbar).
Input
PI91104
Max Pos
100.00
ST
20.00
Set Val
1335
Min Pos
35.00
Gp
-0.5000
Max Chg
5.00
Gi
-0.020
Min Chg
0.20
Gd
0.000
4. EV91127
Separator level LL91113 is used to control the
separator throttle valve EV91127.
Input
LL91113
Max Pos
0.300
ST
10.00
Set Val
90.000
Min Pos
0.0500
Gp
0.0010
Max Chg
0.150
Gi
0.0005
Min Chg
0.005
Gd
0.0000
5. EV91120
Liquid level meter LL91112 is used to control
the Run valve so that a constant level of LHe is maintained in
tailpiece.
