American Magnetics 4Q1010PS-430 Integrated Power Supply System - Manual (Page 107)

Rev. 5 89
Operation
External Rampdown : External Rampdown while in Persistent Mode
a preset level. When appropriately connected to the Model 430
Programmer, these contacts can signal the Model 430 to safely and
automatically ramp the magnet field to zero, thereby preventing a magnet
quench due to low helium level in the system.
3.16.1 External Rampdown while in Persistent Mode
The following steps and associated screen displays describe the process
that occurs after external rampdown is initiated while the magnet is in
persistent mode:
1. The Model 430 Programmer first ramps the power supply to the
magnet current.
2. Once the power supply is at the magnet current, the FIELD AT
TARGET LED will light and the unit will momentarily “hold”:
3. Following a short “hold”, the persistent switch will be heated to
place the power supply in control of magnet current:
4. After heating (turning off) the persistent switch, the MAGNET IN
PERSISTENT MODE LED extinguishes, and rampdown begins.
The FIELD AT TARGET LED extinguishes.
5. After rampdown, the following will display:
+3.92 A
 Mode: Ramping
+0.17 Vs PSwitch Heater: OFF
+50.00 A - Mode: Holding
+2.11 Vs PSwitch Heater: OFF
+50.00 A Mode: Heating Switch (4)
+2.11 Vs PSwitch Heater: ON
+48.85 A
 Mode: Zeroing Current
+1.89 Vs PSwitch Heater: ON
+0.00 A - Ext. Rampdown completed
-0.00 Vs Press ENTER to continue