110
R
EV
9
A
MERICAN
M
AGNETICS
, I
NC
.
O
PERATION
: R
AMPING
F
UNCTIONS
R
AMPING
F
UNCTIONS
The ramping functions are used to control charging of the
superconducting load. The Model 430 Programmer allows piecewise-
linear charging profiles to be defined and executed (up to 10 segments,
each with a unique ramp rate). The basic charging equation for a
superconducting magnet is:
where
V
is the charging voltage (V),
L
is the magnet inductance (H), and
di/dt
is the ramp rate (A/s). The relationship may also be defined in terms
of a ramp rate in kG/s by the relationship:
where
C
is the coil constant (or field-to-current ratio) in kG/A, and
dB/dt
is the ramp rate expressed in kG/s.
A desired ramp rate should be selected by the user and entered into the
Model 430 Programmer. A Voltage Limit should also be specified that is
greater than or equal to the voltage calculated from the equations above
plus energy absorber voltage (if installed) plus power lead voltage drop
(usually less than 2 V).
Once the ramp rate and Voltage Limit are specified, the Model 430
Programmer provides two modes of ramping:
manual
and
automatic
.
Manual ramping will ramp to the Current Limit via manual direction
control by the user. Automatic ramping will ramp to the target field/
current automatically. Automatic ramping can be thought of as a “next
point” operation, whereby the Model 430 determines the appropriate
ramp direction based on the present magnet current and the target
value.
NOTE
You may enter up to 10 digits beyond the decimal point within the
ramping control menus. These extra digits are maintained in the
internal memory of the Model 430 Programmer even though the
full precision is not displayed after entry.
R
AMPING
S
TATES
AND
C
ONTROLS
The ramping state may be one of several values as described in the
table below.
If the
RAMP / PAUSE
key is pressed while ramping, the PAUSED mode
becomes active. To begin automatic ramping, press the
RAMP / PAUSE
key to deactivate the PAUSED mode. If manual ramping is desired, use
V
L
i
d
t
d
----
=
V
L
C
----
B
d
t
d
------
=
Summary of Contents for 430
Page 2: ......
Page 16: ...XVI REV 9 AMERICAN MAGNETICS INC FOREWORD SAFETY SUMMARY ...
Page 28: ...12 REV 9 AMERICAN MAGNETICS INC INTRODUCTION OPERATING CHARACTERISTICS ...
Page 64: ...48 REV 9 AMERICAN MAGNETICS INC INSTALLATION POWER UP AND TEST PROCEDURE ...
Page 208: ...192 REV 9 AMERICAN MAGNETICS INC SERVICE RETURN AUTHORIZATION ...
Page 248: ...232 REV 9 AMERICAN MAGNETICS INC APPENDIX SHORT SAMPLE MODE ...
