Appendix – American Magnetics 05300PS-430-601 High Stability Integrated Power Supply System User Manual

Page 193

Rev. 5

175

Appendix

Model 601 and Energy Absorption

continues to flow driven by the self-induced magnet voltage

(refer to

With a 4-quadrant power supply capable of reversing both the current and

voltage, the power supply voltage would reduce to zero volts and

ultimately reverse as necessary to control the current downward.

However, a unipolar power supply cannot reverse polarity. With no outside

voltage to reduce the current, it continues to flow at the previous rate,

decaying only at the natural time-constant of the circuit inductance and

resistance, T

sec

= L / R.

The current will be reduced by 63% during each

successive time constant period T. With a typical inductance of 50 Henries

and lead resistance of 0.001 Ohms, (T = 50,000 seconds), it will take over

14 hours to decay to 37%, and many times that to reduce to near zero.

Introduction of the Model 601 Energy Absorber provides the solution,

allowing Model 430 Programmer control of both magnet charge and

1. Magnet power supply design is such that the output resistance is

essentially zero resulting in no significant IR drop at the supply termi-
nals.

Figure A-6.

Loop Voltages - Magnet Passively Discharging