List of PID Loops

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.

Input	LL91112	Max Pos	0.7500	ST	20.00
Set Val	75.000	Min Pos	0.0500	Gp	0.0010
		Max Chg	0.150	Gi	0.0020
		Min Chg	0.02	Gd	0.0000