AMI 420, Installation, Operation And Maintenance Instructions, Page: 73 / 134

Rev. 7
55
Operation
Ramping Functions : Manual and Programmed Modes
If the key is pressed, the Model 420 will ramp down at the ramp rate
setting. The ramping may be paused by pressing the key again (or by
pressing
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) to deactivate the manual down mode.
The manual up or down modes will continue ramping until paused or the
current limit for the magnet specified in setup (see paragraph 3.2.2.3) is
achieved.
3.3.3 Ramping in Programmed Mode
Ramping in programmed mode differs from the manual mode in that the
Model 420 automatically performs ramping in the appropriate direction to
achieve the value of the programmed current setting. Programmed mode is
active when the
or keys for the
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are not illuminated,
and the
5$033$86(
key is not illuminated.
3.3.3.1 Programmed Current/Field
The programmed current is accessed by pressing the
352*5$00('&855(17),(/'
key and may be set less than or
equal to the current limit for the magnet specified in setup (see
paragraph 3.2.2.3). The programmed current requires a sign since
it locates a single setpoint within the entire operating current
range of the system.
If the selected default display mode contains field units, the display
will allow entry of a programmed field value in units of kilogauss
(or Tesla) as shown below. The programmed field must also be set
within the current limit for the magnet.
The programmed current/field setting may be entered directly via
the keypad, or adjusted using the dial if the PAUSED mode is not
active (see paragraph 3.3.5 if PAUSED is active). Attempts to set
the programmed current/field above the current limit for the
magnet are ignored and, if attempted, the instrument will beep
once indicating an error and revert to the previous value.
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