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PSI 9000 DT Series
3.10.10 Arbitrary function
The arbitrary (freely definable) function offers the user further scope. There are 99 sequence points available to
run on either current I or voltage U, which all have the same parameters, but can be differently configured so that
standard functions (triangle, rectangle etc.) can be generated or complex curves can be “constructed”. These 99
sequence points or a part of them can run in a sequence point block and this block can then be repeated up to
999 times or endlessly. All sequence points are either assigned to output current or output voltage, thus a mix of
assignment isn’t possible.
The arbitrary curve can overlay a linear progression (DC) with a sine curve (AC) whose amplitude and frequency
is shaped between start and end. When both, start frequency and end frequency, are 0 Hz the AC overlay has no
impact and only the DC part is effective. Each sequence point is allocated a sequence point time in which the AC/
DC curve from start to end will be generated.
The following parameters can be configured for each sequence point:
Value
Range
Description
Is(AC) / Ie(AC)
0...50% of I
Nom
Start/end amplitude of the sine wave part (I mode)
Us(AC) / Ue(AC) 0...50% of U
Nom
Start/end amplitude of the sine wave part (U mode)
fs(1/T) / fe(1/T) 0 Hz...10000 Hz
Start/end frequency of the sine wave part (AC)
Angle
0°...359°
Start angle of the sine wave part (AC)
Is(DC)
Is(AC)...(I
Nom
- Is(AC))
Start value of the DC part (I mode)
Ie(DC)
Ie(AC)...(I
Nom
- Ie(AC))
End value of the DC part (I mode)
Us(DC)
Us(AC)...(U
Nom
- Us(AC))
Start value of the DC part (U mode)
Ue(DC)
Ue(AC)...(U
Nom
- Ue(AC))
End value of the DC part (U mode)
Seq.time
0.1 ms...36000 s
Time for the selected sequence point
The sequence point time (Seq. time) and the start and end frequency are related. The minimum
value for
Δ
f/s is 9.3. Thus, for example, a setting of fs = 1 Hz, fe = 11 Hz and Seq.time = 5 s
would not be accepted as
Δ
f/s is only 2. A seq. time of 1 s would be accepted, or, if the time
remains at 5 s, then fe = 51 Hz must be set.
The amplitude change between start and end is related to the sequence point time. A minimal
change over an extended time isn’t possible and in such a case the device will report an inap-
plicable setting.
After the settings for the selected sequence point are accepted with SAVE, further points can be configured. In a
second settings screen, which is reached by tapping NEXT in the sequence point selection screen, following global
settings for all 99 points are adjustable:
Value
Range
Description
Start seq.
1 ... End seq.
First sequence point in the sequence block
End seq.
Start seq. ... 99
Last sequence point in the sequence block
Seq. Cycles
∞ or 1 ... 999
Number of cycles of the sequence block.
Schematic diagram:
Applications and results:
Sta
rt (D
C)
t
U,I
Seq.time
En
d (
DC
)
Example 1
Focussing 1 cycle of 1 sequence point:
DC values for start and end are the same, also the AC amplitude.
With a frequency >0 a sine wave progression of the set value is
generated with a defined amplitude, frequency and Y-shift (offset,
DC value at start and end)
The number of sine waves per cycle depend on the sequence point
time and the frequency. If the sequence point time were 1 s and the
frequency 1 Hz, there would be exactly 1 sine wave. If the time were
0.5 s at the same frequency, there would only be a half sine wave.
If you would adjust the time to match the period of 1 full wave and
you would set the sequence cycles to infinite, it would generate a
permanent sine wave with just 1 sequence point.
Summary of Contents for PSI 9000 DT Series
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