Lakeshore Learning Materials 622 - Manual (Page 78)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
Options & Accessories 6-10
When PSH is ON, the MPS compares the present
current setting with the current setting stored when
PSH was OFF. If the two do not match, the MPS
sounds the alarm for ½ second and displays:
Press a Data Entry up or down arrow to turn ON the
PSH. If Esc is pressed, or no key is pressed for
approximately 30 seconds, the PSH is not turned
ON.
6.3.3 Model 6228-8MUX Operation
The 6226-8MUX is a persistence card with a
multiplexed output. The output specifications are the
same as the single 6228 option card. The heater
supply current connects to one of eight persistence
heaters. The PSH SETUP screen displays an
additional line indicating the channel active if the
heater is turned on. To change channels, access
the PSH SETUP screen, move the cursor to the
CHANNEL line, and use the Data Entry up and
down arrows to increment to the desired channel.
Select Channel 0 to force the heater off.
If the heater is on and connected to a channel,
changing channels may cause problems. A warning
displays to prevent a mishap.
The Normal Manual screen shows which channel
connects to the heater when the heater turns on
(persistence off). When a zero displays, the heater
is off and not connected to any of the multiplexed
outputs. When a 1 through 8 displays, then that
multiplexed channel is controlled.
The magnet is put in and taken out of persistence via the last line on the Normal Manual Screen as with the
6228 PSH card. To change the channel number, access the Normal Manual Screen, use the Right/Left Cursor
to move to the channel number, and then use the numerical keypad entry keys. The data Entry up or down
arrow toggles the persistence on and off.
The Automatic Mode shown to the right allows
channel selection on line 7 prior to running the
Automatic change of persistence current.
To change the channel number on the Automatic
Screen, use the Right/Left Cursor to move to the
channel number, and then use the numerical
keypad entry keys. The Data Entry up or down arrow
does not toggle persistence on and off. Persistence toggles on and off automatically.
6.3.4 PSH Card Voltage Constraints
The PSH (Persistence Switch Heater) card of the MPS supplies a current to a resistance heating element to
"normal" a persistence wire opening the ends of a supercooled magnet to enable charge (current) change.
Program current from 0 to 124 mA through the PSH Setup screen. Three conditions must be met when
selecting an appropriate current:
1. The current must be enough to "normal" the switch element. The magnet manufacturer specifies this
current and the heater resistance. This current must fall between the two following extremes.
2. The selected current multiplied by the heater resistance (e = i × r) must be greater than 0.65 Vdc for the
MPS to accurately determine switch status when heated. If less than 0.65 Vdc, the MPS may not properly
report switch mode.
C A U T I O N ! S E T T I N G N O T S A M E A S S A V E D V A L U E
L A S T P E R S I S T E N C E C U R R E N T :
P R E S E N T S U P P L Y C U R R E N T :
E N T E R K E Y T O C H A N G E T O L A S T P E R S I S T E N C E
C U R R E N T , W A I T R U N U P D E L A Y , T H E N T U R N O F F .
¥ K E Y T O T U R N O F F A T P R E S E N T C U R R E N T .
E s c K E Y T O A B O R T .
H E A T E R C U R R E N T : 5 0 m A
1 0 . 0 0 0 A
5 . 0 0 0 A
O U T P U T S : *
+2.000A
+ 1 . 0 0 0 V
S E T T I N G S :
+2.000A
C O M P L I A N C E
R A M P R A T E
R A M P E N A B L E
¤ C H 1 , P E R S .
: + 5 . 0 0 0 V
: + 1 . 0 0 0 A / S
: < O F F > ¥
: < O N > ¥
P E R S I S T E N C E H T R S E T U P :
¤ H E A T E R
S T A T U S
L A S T E N D
C H A N N E L
O U T P U T S : *
+2.000A : 5 0 m A
: < H T R O N >
: + 0 . 0 0 0 A
: 1 ¥ + 0 . 0 0 0 V
P E R S I S T E N C E H T R S E T U P :
¤ H E A T E R
S T A T U S
L A S T E N D
T H E H E A T E R I S O N .
C A N N O T C H A N G E C H A N N E L
W I T H T H E H E A T E R O N .
E s c T O C O N T I N U E .
O U T P U T S : *
+2.000A : 5 0 m A
: < H T R O N >
: + 0 . 0 0 0 A
+ 0 . 0 0 0 V
A U T O M A T I C M O D E :
¤ M G T S T A R T
M G T E N D
M G T R A T E
P E R S R A T E
L A S T E N D
C H 1 , P E R S .
R U N ¥
O U T P U T S : *
+0.000A : 1 0 . 0 0 0 A
: 1 5 . 0 0 0 A
: 1 . 0 0 0 A / S
: 1 . 0 0 0 A / S
: 1 0 . 0 0 0 A
: < O N >
+ 0 . 0 0 1 V
S T A N D B Y