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EPS Stromversorgung GmbH
Alter Postweg 101 • 86159 Augsburg
Germany
Fon: +49 821 / 570451-0
Fax: +49 821 / 570451-25
www.eps-germany.de
PSI 9000 2U Series
3.10.2.3 Resolution of X (Time) and Y (Amplitude)
For functions, the device can resolve 52428 steps in the effective range of 0 ... 100%. Intermediate steps to create
a linear or other rise/fall are calculated depending on the amplitude and then set.
If the amplitude is very low and the time long, only few steps will be set as otherwise many identical values will be
set one after another, generating a staircase effect.
3.10.2.4 Possible technical complications
Operation of switching mode power supplies as a voltage source can, when applying a function to the output volt-
age, lead to damage of the output capacitors due to continuous charging/discharging which causes overheating.
Furthermore the actual voltage progression may differ from what’s expected.
3.10.2.5 Minimum slope / maximum ramp time
When using a rising or falling offset (i.e. DC part) at functions like ramp, trapezoid, triangle and even sine wave,
a minimum slope, calculated from the rated values of voltage or current, is required or else the adjusted settings
would be neglected by the device. Calculating the minimum slope can help to determine if a certain ramp over
time can be achieved by the device or not. Example: model PSI 9080-120 2U is going to be used, with 80 V and
120 A rating.
Formula: minimum slope = 0.000725 * rated value / s
. For the example model it results in ΔU/Δt of
58 mV/s and ΔI/Δt of 87 mA/s. The maximum time which can be achieved with the minimum slope then calculates
as approximately 1379 seconds according to formula
t
Max
= rated value / min. slope.
3.10.3 Method of operation
In order to understand how the function generator works and how the value settings interact, the following should
be noted:
The device operates, including in function generator mode,always with the three set values U,I and P.
The selected function can be used on one of both the values U or I, the other two are then constants and have
a limiting effect. That means if, for example, a voltage of 10 V is set for the DC output, a load is connected and
a sine wave function should operate on the current with an amplitude of 20 A and offset 20 A, then the function
generator will create a sine wave progression of current between 0 A (min) and 40 A (max), which will result in an
output power between 0 W (min) and 400 W (max).The output power, however, is limited to its set value. If this
was 300 W then, in this case, the current would be limited to 30 A and, if clamped to an oscilloscope, it could be
seen as capped at 30 A and never achieve the target of 40 A.
3.10.4 Manual operation
3.10.4.1 Function selection and control
Via the touchscreen one of the functions described in
can be called
up, configured and controlled. Selection and configuration are only possible
while the output is switched off.
►
How to select a function and adjust parameters
1.
While the DC output is switched off tap the touch area
on the main screen.
2.
In the menu overview tap on the touch area
and then on the desired function.
Note: this touch area is locked in R mode (adjustable resistance).
3.
Depending on the choice of function there follows a request to which value the function generator is going
to be applied:
or
.
4.
Adjust the parameters as you desire, like offset, amplitude and frequency for a sine wave, for example.
5.
Do not forget to adjust the overall limits of voltage, current and power, which you can access with touch
area
.
When entering function generator mode, those limits are reset to safe values, which can prevent
the function from working at all. For example, if you apply the selected function to the output
current, then the overall current limit should not interfere and should at least be as high as
amplitude.
