American Magnetics 430, Installation, Operation And Maintenance Instructions

Page: 75 / 254

R
EV
9 59
A
MERICAN
M
AGNETICS
, I
NC
. O
PERATION
: S
INGLE
-
KEY
C
OMMANDS
/ M
ENUS
switch heater is energized and this key is pressed, the persistent switch
heater is de-energized. If the persistent switch heater is de-energized
and this key is pressed, the persistent switch heater is energized.
NOTE
The power supply output current remains unchanged when
SHIFT + PERSIST. SWITCH CONTROL
is used. Only the
state of the persistent switch heater is changed.
When the persistent switch heater is energized, the Model 430
Programmer is supplying current to the appropriate pins (9 & 10) of the
Magnet Station Connectors in order to drive the persistent switch into a
normal state, which takes the magnet out of persistent mode. Magnet
persistent mode is indicated by the
MAGNET IN PERSISTENT MODE
LED
4
.
The Model 430 Programmer will beep once (indicating an error) if the
user attempts to activate the switch heater control without first indicating
a persistent switch is installed in the Switch submenu and specifying the
switch heating current, switch transition detect method, and the heated
time and cooled time
5
for timer-based transitions.
The nominal switch heating current is listed on the magnet specification
sheet, and may be entered in the Model 430 Programmer by accessing
the Switch submenu
6
. In addition to the
heating current
, the user must
also specify the
switch transition
detection method,
PSw P/S Ramp Rate
and
cooling gain
. If the switch transition is timer-based, then the
heated
time
and
cooled time
must also be specified.
T
IMER
-
BASED
S
WITCH
T
RANSITIONS
The heated time allows the Model 430 Programmer to delay
compensating the internal control logic until the magnet is
guaranteed to be in the circuit. The heated time can be set from a
minimum of 5 seconds to a maximum of 120 seconds within the
Load submenu
7
. The default heating period of 20 seconds is
adequate for the majority of persistent switches. If the magnet
appears unstable just after the switch heating period expires,
increase the switch heated time to allow for complete heating.
The cooled time allows the persistent switch sufficient time to be
cooled to superconducting state before the current is changed in
the magnet. The cooled time can be set from a minimum of 5
seconds to a maximum of 3600 seconds within the Load
submenu
8
. The default cooling period of 20 seconds is adequate
4. See page 70.
5. See page 83 and page 85.
6. See page 85.
7. See page 86.