Current Ramp Rate; Ramp Segments; Pause Ramp; Zero Output - Lakeshore 642 User Manual

Ramp Segments (Continued)
To configure the ramp segments press Ramp Segments. The first ramp segments setup screen appears as a prompt for
the ramp segments mode.

Ramp Segments

Select With °®
Ramp Segments: Enable
Use the s or t key to select the ramp segments mode, either Enable or Disable. Press Enter to accept the new selection
and continue to the next setting screen. Press Escape to cancel the new selection and return to the normal display.
If the ramp segments are enabled, the next ramp segments screen that appears is for entering or editing the ramp
segments table. All five of the ramp segments are shown on the display at the same time. The segments should be
entered in order of increasing current. An entry of 0 A will indicate the end of the table and the instrument will not
search beyond that segment.
Ramp Segments
Current
1: 10.0000 A
2: 15.0000 A
3: 20.0000 A
4: 30.0000 A
5: 40.0000 A
When the segment number is highlighted, use the s or t key to scroll through the ramp segments. Press the Enter key
when the desired segment number is highlighted and continue to the current field.
When the current field is highlighted, use the numerical keypad to enter the upper current setting for that ramp segment
in amps. Press Enter to accept the new selection and continue to the ramp rate field. Press Escape to restart the setting
sequence and enter a new value. Press Escape again to highlight the segment number.
When the ramp rate field is highlighted, use numerical keypad to enter the applicable ramp rate in A/s. Press Enter to
accept the new selection and continue to the next segment. Press Escape to restart the setting sequence and enter a new
value. Press Escape again to highlight the segment number.
Similarly enter or edit all ramp segments. When complete, press the Escape key while the segment number field is
highlighted to exit the ramp segment edit screen and return to the normal display. When output current is called for using
the Output Setting key, the output will ramp to the desired current using the ramp segment set points.
4.9

PAUSE RAMP

The Pause Ramp key will pause the output current ramp within two seconds after the key is pressed. While the output
current ramp is paused, the Ramping LED will blink. Pressing the Pause Ramp key again will continue the ramping.
Pressing the Enter key while the ramp is paused will set the current at the paused setting and exit the Pause Ramp
mode.
4.10

ZERO OUTPUT

The Zero Output key on the front panel can be used to set the output current to 0 A. When the Zero Output key is
pressed, the current output will begin to ramp down using the current ramp rate. This key is equivalent to using the
Output Setting key and entering 0 A except that it works even when the Model 642 is being programmed externally.
Refer to Paragraph 4.6 to set the output current.
NOTE: The current ramp rate applies only to the internal current output setting. When the Model 642 is
programmed externally, the drop to zero output (when the Zero Output key is pressed) will be quite rapid
(~1 second) and limited primarily by the magnet reactance and the Model 642 voltage compliance limit.
The voltage compliance LED may light during the change.
4-6
Lake Shore Model 642 Electromagnet Power Supply User's Manual
Ramp Rate
1.0000 A/s
0.8000 A/s
0.7000 A/s
0.6000 A/s
0.5000 A/s
Operation