Programmer User guide

Model 430 Features
• Parameter for setting persistent switch cool time
1
• Ultrahigh resolution and accuracy
• Intuitive user operation and comprehensive manual
2
• Upper current limit and voltage limit settings
• Easy to read digital V
m
/V
s
(magnet and supply voltage) display meter
• Can automatically determine inductance of load
• Drivers for LabView
• User-adjustable threshold quench detection with detection I/O
• Automatic ramp down and quench inputs
• Galvanically isolated Program Output signal to prevent ground loops
• Multifunction vacuum fluorescent display (VFD)
• Menu driven user interface and keypad – logical and intuitive
• One touch Ramp/Pause button
• Digital readout in Field (kilogauss or Tesla) or Current (Amperes)
• Control multiple parallel or series configured supplies
• Front panel indication that current is flowing in magnet leads
• Velocity sensitive encoder dial for fine adjustments
• Programmable piecewise-continuous ramping with 10 current-
dependent rates
• Output signals to helium level and temperature instruments via internal wiring from the magnet station connector
• Integrated DB-25 magnet
station connector with wired
DB-25 output signals available
for other system devices
• Built-in Ethernet and RS-232
3
communication interfaces
• Ethernet port allows access to the Programmer across a local network or via the Internet
• Operating software is stored in flash memory and can easily be updated via the Ethernet or RS-232 ports
1
Important for conduction-cooled magnets (dry switch) when a relatively long time is required to cool as compared with wet switches.
2
Manual is conveniently available in the Model 430 firmware (pdf format) - just access the instrument’s IP address via a web browser.
3
An optional external conversion unit is available for interfacing the RS-232 serial port to a GPIB bus.
Simplified Operation
Most frequently used functions are accessible via single keystroke or shift plus keystroke. The front panel velocity-accelerated rotary encoder
dial also allows the operator to make fine adjustments to operating parameters of the magnet system. Magnet system signal wiring, such as
magnet voltage/current, helium levels, and temperatures, connect to the rear panel through a single DB-25 connector. Multiple connectors on
the rear panel allow the user to route the signals to the appropriate instruments at the control station; the need for complicated wiring
between the cryostat and magnet control station is thus eliminated.
Digital Control
The digitally-based Model 430 incorporates very high resolution analog <> digital converters and digital signal processing (DSP) to achieve
excellent stability, precise control, and superior current resolution of the programmed magnetic field. An internal microcomputer manages all
computations, analog data conversion, display/keypad functions, communications I/O, and analog power supply programming signals.
High Resolution and Stability
Precision instrumentation techniques and potentiometer-free designs are employed throughout the instrument to ensure accurate signal
translation for a wide range of conditions. The magnet current is sampled at a resolution of 15.6 µA (for a 125 A supply) and is front-panel
programmable in 0.1 mA increments. A further order of magnitude in accuracy and stability can be achieved by choosing the optional
fluxgate based current measurement system in place of the standard resistive shunt.
Magnet Control and Protection
The Model 430 protects the magnet from runaway supply voltage/current or operator error. The quench detect function, with user-adjustable
quench sensitivity, is designed to detect a magnet quench and quickly stop power from being delivered to the resistive magnet. The system
can optionally incorporate an AMI Liquid Helium (LHe) Level Instrument to prevent magnet quenching due to low LHe level; automatic ramp
down of the magnet (even in persistent mode) is initiated if the LHe level drops to a preset level.
A system administrator can program the instrument (from the front panel or remotely) with password protected operational limits or any other
parameter(s) which can thereafter not be exceeded or changed without the password. During operation of the system, if the operator
inadvertently attempts to take the magnet system to an excessive magnetic field strength or excessive voltage, the Programmer will not
accept the parameter and will alert the operator that the value exceed the limits.
The Model 430 automatically determines and sets the proper persistent switch heater current (range: 0 to 100 mA; compliance 13.5 V). The
persistent switch heater circuit is continually monitored and the user is notified of circuit problems. The Model 430 Programmer automatically
controls the power supply and persistent switch heater to aid the user in safe and quick transitions in and out of persistent mode.