American Magnetics 420 Power Supply Programmer - Manual (Page 27)

Rev. 7 9
Introduction
Operating Characteristics
1.5 Operating Characteristics
The Model 420 Programmer has
been designed to perform with
various power supplies to allow
the user the greatest degree of
system flexibility. The power sup-
ply and programmer combination
will be categorized by one of four
forms: single-quadrant, dual-
quadrant, simulated four-quad-
rant, and true four-quadrant. For
sake of clarity, the term quadrant
is defined as one of four areas of a
cartesian coordinate system
where the abscissa is current and
the ordinate is voltage. Refer to
Figure 1-1.
1.5.1 Single-Quadrant Operation
The simplest form of a programmer-power supply system is the single
quadrant system as illustrated in Figure 1-2. The system is comprised of a
Model 420 Programmer, unipolar power supply, and superconducting
magnet. This system allows current to flow in a single direction in the
magnet thereby giving a magnetic field vector of varying magnitude but in
a single direction. This corresponds to operating in quadrant 1 of Figure
1-1. The electrical energy can be stored as magnetic energy as fast as the
magnet and power supply voltage will allow. In order to reduce the
magnetic field, the magnetic energy is converted to electrical energy and
then to thermal energy in the resistive elements of the system. The size of
the resistive elements determines how fast the magnetic field can be
collapsed and is typically very slow in the single-quadrant system.
20
-20
200 -200
V
I
Positive Current
Flow Direction
Positive Voltage
Polarity
Positive Current
Flow Direction
Negative Voltage
Polarity
Negative Current
Flow Direction
Positive Voltage
Polarity
Negative Current
Flow Direction
Negative Voltage
Polarity
1 2
4 3
Figure 1-1. The four regions, or
quadrants, of system operation.
Magnet
Coil(s)
Persistent
Switch
(optional)
Misc. Line Losses
Model 420
Shunt
V Unipolar
Power Supply
Current
Figure 1-2. Single-Quadrant Magnet System