Maximum Setting Limits; Maximum Output Current; Maximum Current Ramp Rate - Lakeshore 642 User Manual

4.11

MAXIMUM SETTING LIMITS

The Model 642 offers a maximum setting limit for output current and ramp rate. Typical properties of the magnet will
dictate these parameters. These maximum parameters should be entered before the magnet system is used to prevent
damage.
4.11.1

Maximum Output Current

Maximum Output Current limits the output current that can be entered. This setting will only limit the internal output
current setting. If the output current is being programmed by an external voltage, then some external provision must be
made to insure that the programming voltage will never exceed the desired output current. See Paragraph 4.15 to setup
the External Current Programming mode.
To set the maximum output current limit press Max Settings. The first maximum setting screen appears as a prompt for
the maximum output current limit.
Maximum Settings
Enter a Value For
Max Current: 60.0000 A
Use the data entry keys to enter the maximum output current limit value between 0.0000 and 70.0000 A. 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.
NOTE: The maximum output current limit value can be set as high as 70.1000 A. This can be used to compensate
for variances in calibration. The output current is guaranteed to reach a minimum of 70 A into a 0.5-ohm
load but may not be able to reach 70.1 A in all circumstances.
4.11.2

Maximum Current Ramp Rate

Maximum Current Ramp Rate limits the maximum current ramp rate that can be entered. This setting will only limit the
internal output current ramp setting. If ramp segments are being used, this setting will also limit the ramp rate that can be
set by a ramp segment. Refer to Paragraph 4.8 to setup Ramp Segments.
To enter a value for the maximum current ramp rate limit, continue from the maximum current screen or press Max
Settings then Enter until the following display setup screen appears as a prompt for the maximum current ramp rate
limit.
Use the data entry keys to enter the maximum current ramp rate limit value between 0.0001 and 99.999 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.
Maximum Settings
Enter a Value For
Max Ramp Rate: 1.0000 A/s
Operation
Lake Shore Model 642 Electromagnet Power Supply User's Manual
4-7