Lakeshore Learning Materials 622 - Manual (Page 28)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
Operation 3-2
3.2 POWER UP
Read and follow instructions in Paragraphs 2.1 - 2.4.3 and the Forward safety recommendations before
applying power to the MPS. Do not connect the MPS to the magnet yet. Short the output terminals together
with a #4 gauge or larger cable to protect the magnet against incorrect configurations.
Turn on the MPS. It requires approximately 2 seconds for initialization. Initially, all front panel annunciators
come on and the alarm sounds for a short time. Within 1 second, the Fault and Persistent Switch Heater On
annunciators and the alarm turn off. If the MPS detects a high or low AC line fault, it blinks the front panel
Fault annunciator and turns off the input circuit breaker. If this occurs, verify that the AC source matches the
line voltage listed on the MPS rear panel.
Initially, the entire display clears and the alarm sounds for a short time. The MPS initializes itself and displays
the model identification. The Normal Display screen appears with a blinking asterisk indicating each update
when the unit is in normal operation.
Depending on the existence of the PSH Option Card and the mode of operation, the MPS displays one of
three possible Normal Displays on power up: one for Manual Mode (no PSH Option Card), one for Manual
PSH Control, or one for Automatic PSH Control. The factory-preset is the Normal Display for Manual Mode,
but the MPS remembers the last PSH mode selected at power down and powers up in that mode. Without an
PSH option installed, the MPS powers up in the Normal Display for Manual Mode.
Set Magnet Ramp Rate and Persistence Switch Ramp Rate in the Normal Display screen. Set Field Units,
Maximum Current, and Compliance Voltage in the Instrument Setup Screen. Set Current Step Limit in the
Step Limit/Zero screen.
CAUTION: Set magnet parameters according to manufacturer's specifications. Failure to do so may
damage the magnet and threaten user safety.
3.3 NORMAL DISPLAY FOR MANUAL MODE
Shown to the right is the default startup Normal
Display for Manual Mode. For operation with the
PSH card installed see Paragraph 3.4 for MANUAL
persistence mode or Paragraph 3.5 for
AUTOMATIC persistence mode.
The Normal Display screen allows entry of MPS
output current (or field) settings at any time. Settings
cannot exceed limits in the INSTRUMENT SETUP screen. The OUTPUTS portion of the screen indicates
output values and computer interface status. The Normal Display key returns the display to this screen at any
time.
Use the Cursor keys to move the line indicator up or down. Parameters with a ¥ icon toggle with the Data
Entry up or down key. Change all others using any numeric entry mode, including the cursor.
CURRENT / FIELD:
MPS Output Setting. This line reads CURRENT if set to display amps and FIELD if set to display computed
field (see Paragraph 3.6.1.4). To set MPS output, move to the CURRENT / FIELD line and enter the new
setting. If RAMP ENABLE is ON, the current or computed field ramps to the new setting at the displayed
RAMP RATE. If RAMP ENABLE is OFF, the current or field changes to the new value immediately or to the
value that causes MPS voltage COMPLIANCE. However, it is not recommended to operate the MPS with
RAMP ENABLE OFF; it may cause a magnet quench (see Forward).
COMPLIANCE (Read only):
Compliance Setting. Change the COMPLIANCE voltage in the INSTRUMENT SETUP screen (See Paragraph
3.6.1.4).
RAMP RATE:
Ramp Rate Setting. Exceeding the maximum rated magnet voltage or current ramp rate may damage the
magnet. Users may configure the MPS to limit the voltage by adjusting the compliance. If RAMP ENABLE is
ON, RAMP RATE controls the rate at which the magnet current reaches the current setpoint as long as the
MPS does not go into compliance. (See Paragraph 3.6.1.4).
NOTE: To pause or restart a ramp, press either the Data Entry up or down key. To abort a ramp, press Esc.
O U T P U T S : *
+1.999A
+ 0 . 0 0 1 V
S E T T I N G S :
¤
+ 0.1999A
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
: § 1 . 0 0 0 V
: § 1 . 0 0 0 A / S
: < O F F > ¥