American Magnetics 05300PS-430-601 High Stability Integrated Power Supply System - Manual (Page 39)

Rev. 5 21
Installation
Power-Up Procedure
appears to lag, then decrease the stability setting until the system is
responsive. If the current appears to oscillate, increase the stability setting
until the oscillations are damped.
Note
If you have purchased a superconducting magnet with the Model
430 Programmer, AMI will normally provide a recommended
stability setting for optimal operation of the magnet system. If you
operate the Model 430 Programmer with a different load, be sure to
restore the stability setting to the recommended value when the
superconducting magnet is reconnected.
The stability setting is essentially manual control of the gain of an
integrator present in the control logic of the Model 430 Programmer.
Increasing the stability setting decreases the gain of the integrator.
A special case is with the energy absorber designs available from AMI. The
Model 601 Energy Absorber is a nearly infinite-resistance device until 5
Vdc is achieved across its terminals. Once the 5 Vdc “bias” is present, the
Model 601 allows current flow with a nominal 2 mΩ series resistance.
Therefore, the Model 430 Programmer will require an “integration time” to
overcome the 5 Vdc bias. Once the bias is achieved, the series resistance is
minimal and the Model 601 appears as a short-circuit. It is not possible to
decrease the stability setting to remove the integration time, since once
the 5 Vdc bias is achieved, the load is a short-circuit and the system will
become unstable.
However, when operating with a superconducting magnet in the circuit,
the integration gain of the Model 430 Programmer will be adequate to
quickly “bias” the Model 601 and achieve a proper current ramping profile.
The only time the “integration time” is long is when an energy absorber is
used, and the load is a short circuit.
2.9 Power-Up and Test Procedure
It is important to verify that the magnet system has been properly
connected before the superconducting magnet is energized. This is
especially recommended if the system is to be controlled via a computer
since this setup will allow software debugging without the potential for
damage to the magnet. The following procedures will assist the user in the
verifying key system components.
1. Using the appropriate diagram from section 2.5 as a guide, verify
all system components are connected as shown. If there is any
doubt as to the correct connection of a component, contact an AMI
Technical Support Representative. The user may be required to