Lake Shore 625, User Manual

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Lake Shore Model 625 Superconducting MPS User’s Manual
Operation 4-15
Use the data entry keys to enter the current step limit value between 0.0100 and 10.000 A/s. Press Enter to accept the
new value. Press Escape to restart the setting sequence and enter a different value. Press Escape again to leave the
setting sequence.
4.17 ERROR STATUS DISPLAY
Error messages appear on the lower part of the instrument display when it identifies a problem during operation. The
Fault LED will also light to indicate error conditions, blinking for operational errors, on solid for instrument hardware
errors. Refer to Paragraph 7.6 for a listing of all the error conditions. When an error condition occurs, the name of the
error is shown in the lower part of the display alternately with “Press Status Key for More Info.” Pressing the
Status key
will bring up a screen that will show an extended description of the error. An example of how the magnet quench error is
shown on the main display is given below.
Output I Output V
+ 0.0126
A
+0.1346
V
Set: + 0.0000 A V Limit: 5.0000 V
Rate: 0.1000 A/s V Sense: +0.0085 V
*** Magnet Quench Detected ***
PSH On: 40 mA
To enter the error status display press Status while in the main display. A screen similar to the one shown below
appears. This screen will differ depending on the error that is being displayed. If there are no errors to report, the display
will show “No errors reported.” The following example shows the description for the magnet quench error.
Magnet quench detected. Current output set
to 0. Normal operation will not be resumed
until the magnet is completely discharged.
Press Status to attempt to clear error.
4.18 EXTERNAL CURRENT PROGRAMMING
The output current of the Model 625 can be set internally, externally, or by the sum of the external and internal settings.
Normally, the current is controlled internally by entering a setting from the front panel using the
Output Setting key.
Refer to Paragraph 4.5 to set the output current. When the external program mode is set to External, the front panel
setting is fixed at 0 A and the output current is set using an external voltage where 1 V = 10 A. When the external
program mode is set to Sum, the internal and external settings are summed together to set the output current. When using
the External or Sum modes, care must be taken to insure that the output current does not exceed the maximum current for
the magnet. The software maximum setting limits cannot limit the output current that is set when using the External or
Sum modes. A 40 Hz, low-pass filter limits the bandwidth of the external current programming input. The bandwidth of
the output is also limited by the compliance voltage and the inductance of the magnet. See Paragraph 2.2.2 for a
description of the relationship between voltage and inductance.
To configure the external current program mode press External Program . The following setup screen appears as a
prompt for the external current program mode.
External Program Mode
Select With °®
External Program Mode: Internal