Rev. 5
79
Operation
Ramping Functions
3.12 Ramping Functions
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.
3.12.1 Ramping States and Controls
The ramping state may be one of several values as described in Table 3-6.
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
either the
INCR. FIELD
or
DECR. FIELD
SHIFT-key for manual control of
ramping up or ramping down, respectively.
V
L
i
d
t
d
----
=
V
L
C
----
B
d
t
d
------
=
Summary of Contents for 05100PS-430-601
Page 2: ......
Page 10: ...x Rev 5 List of Figures ...
Page 12: ...xii Rev 5 List of Tables ...
Page 18: ...xviii Rev 5 Foreword Safety Summary ...
Page 30: ...12 Rev 5 Introduction Operating Characteristics ...
Page 42: ...24 Rev 3 Installation Power Up Procedure ...
Page 114: ...96 Rev 5 Operation Summary of Operational Limits ...
Page 156: ...138 Rev 5 Remote Interface Reference Error Messages ...
Page 168: ...150 Rev 5 Service Return Authorization ...
Page 226: ...208 Rev 5 Index ...
