The 4Q06125PS-420 Power Supply System consists of an AMI Model 420 Programmer, configured for 125 Ampere operation, and an AMI 4Q06125PS DC Power Supply.

Model 4Q06125PS-420 is a true 4-quadrant programmable voltage and current superconducting magnet power supply, meaning it is capable of both sourcing and sinking power. The Model 4Q06125PS power supply is rated at ±6 Volts, ±125 Amperes. The power supply passes smoothly through zero to provide true ± voltage and ± current. The Model 4Q06125PS power supply uses switch mode technology for efficient operation. A bi-directional, isolating, power-factor-correcting (PFC) a-c input circuit recuperates energy from an active load and sends it back into the line to maintain low dissipation and provide energy conservation. The Model 4Q06125PS-420 system provides for finely-controlled charging of the inductive superconducting magnet load and eliminates magnet current oscillations.

The power supply is designed for remote voltage programming (i.e. voltage-to-voltage mode) to function as a slaved supply to the Model 420 Power Supply Programmer.

The true, four-quadrant output capability of the Model 4Q06125PS-420 Power Supply System is ideal for the charge and discharge cycling of superconducting magnet loads. The versatile Model 420 Digital Programmer controls the Model 4Q06125 Power Supply and the combination has the ability to set either positive or negative current or voltage values. This true, four-quadrant operation significantly simplifies test procedures as well as system design by eliminating the need for external switching or operator intervention to reverse the direction of the current. The transition through zero current is smooth and continuous allowing the user to readily analyze samples at very small current increments about zero. Extensive output filtering and ripple cancellation circuitry was designed into the Model 4Q06125PS-420 to minimize the noise at the output.

Superior Resolution and Stability

The Model 420 Programmer utilizes 20-bit converters to translate signals between the analog and digital domains. 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 20µA. The encoder dial allows for fine adjustment at up to 15-digits resolution. All pause and hold functions are performed in the digital domain, which provides for excellent stability and low drift (<0.01%) of the programmed magnetic field.

Programmable Safety Features

The Model 420 Programmer is designed to allow the operator to program the system from the front panel, or remotely, with current and voltage limit parameters which will not be exceeded during operation of the system. Once set, should an operator inadvertently attempt to operate beyond the specified limits, the programmer will not accept the parameter and audibly beep. An appropriate error message is available via the remote interface. The Model 420 Programmer also automatically limits the charge rate of the magnet to the specified voltage limit.

The power supply system is also protected from any over-voltage, over-current, or over-temperature conditions.

Quench Detection

The Model 420 Programmer provides visual indication of a magnet quench and automatically commands the power supply output voltage to zero volts. The operator is prevented from initiating a recharge of the magnet until the Model 420 front panel quench detection switch is reset. A rear-panel input is also available to accept a user- generated quench indication, if required.

Standard Remote Interface

The Model 420 Programmer provides an RS-232 (or optional RS-422) serial port as well as an IEEE-488 parallel port as standard features. In contrast to other magnet power supply system designs, an expensive additional analog-to-digital conversion system is not required to collect data via a host computer. All settings can be controlled via the remote interfaces and the front panel can be remotely locked to prevent accidental operation. The Model 420 also provides trigger functions for data collection and/or logging during operation.