User Manual

Rev. 5 35

Operation

Single-key Commands : Target Field Setpoint

seconds within the Load submenu

. The default cooling period of 20

seconds is adequate for the majority of wet persistent switches.

Conduction cooled switches typically require longer time to transition from

resistive to superconducting.

The default cooling gain of 0.0% may be adequate for the majority of wet

persistent switches. However, this setting may result in some magnet drift

during persistent switch cooling, especially with conduction cooled

switches. Increasing the cooling gain adds control loop gain during the

switch cooling cycle. Too little may result in magnet drift during switch

cooling. Too much may result in power supply instability during switch

cooling, which could potentially prevent the switch from cooling. Most

systems requiring some cooling gain to control magnet drift will likely

work with value set to 25%.

Note

During the period the switch is being heated or cooled, the Model

430 Programmer will not allow ramping functions to be executed

and will beep once if the user attempts to initiate a ramping

operation.

Refer to section 3.13 on page 81 for a complete description of magnet

persistent switch control. A flowchart of the persistent switch control

functions are located in the Appendix beginning on page 199.

3.6.2 Target Field Setpoint Key

Pressing the TARGET FIELD SETPOINT key provides a menu for setting

the target field/current. The target field/current is the field or current to

which the Model 430 Programmer ramps the superconducting magnet

when it is not paused. The target field/current may be set to the lesser of

(1) the Magnet Current Rating, and (2) the Current Limit

or equivalent

field (per defined coil constant). The target field/current does not require a

sign (attempting to enter a negative value will cause the Model 430

Programmer to produce one beep to indicate an error).

When on the default display, pressing the

SHIFT + TARGET FIELD

SETPOINT

keys will temporarily display the Magnet Current/Field for

1. Refer to section 3.10.2.10 on page 60.

2. Refer to section 3.10.2.4 on page 56.

+50.00 A - Target Field (kG)

+0.50 Vs +50.000