User Manual

Page 62
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
[e-mail]
PSB 9000 2.5 kW Series
3.11.2.3 Resolution
Amplitudesgeneratedbythearbitrarygeneratorhaveane󰀨ectiveresolutionofapprox.52428steps.Iftheam-
plitude is very low and the time long, the device would generate less steps and set multiple identical values after
another,generatingastaircasee󰀨ect.It’sfurthermorenotpossibletogenerateeverypossiblecombinationoftime
and a varying amplitude (slope).
3.11.2.4 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di󰀨erfromwhat’sexpected.
3.11.2.5 Minimum slope / maximum ramp time
Whenusingarisingorfallingo󰀨set(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 PSB 9080-120 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.
3.11.3 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 applied to U or I set value, while all other set values are then constants and have a
limitinge󰀨ect.
That means if, for example, a voltage of 10 V is set in source mode 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o󰀨set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). But in case the output power would be limited to, for instance,
300 W, the current would be limited to 30 A and, if clamped to an oscilloscope, it would be seen to be truncated at
30 A and never reach the target of 40 A.
For an even better understanding how the device works in dynamic operation read following:
• The device also has an integrated electronic load, here called “sink”, which is supposed to
discharge the capacities on the DC terminal of the device when running dynamic voltage
changes in source mode, i.e higher voltage to lower voltage. This requires a certain current
and thus power, which can and should be adjusted for almost every function described below
(parameters “I Sink” and “P Sink”). For safety reasons, the current value “I Sink” is always set
to0afterselectingafunctionforconguration,thusdeactivatingsinkmode.
• The sink current, as adjustable with parameter “I Sink”, when being set to > 0, would also
discharge capacities being present in an external load application or load an external voltage
sourceandthusthiscurrentsettinghastochosencarefully,becauseitalsoa󰀨ectstheneces-
sary cross section of cables. Recommendation: Set I Sink to at least I
Peak
of the resulting curve
Master-slave systems have further characteristics which have to be considered:
Attheendofthecongurationofeverystandardfunctionyouarerequestedtosetupglobal
set values, the so-called “U/I/P limits”. These limits are transferred to all slave units of mas-
ter-slavesystems.It’srecommendedtocarefullycongurethemsotheMSsystemcanwork
as expected and the slaves wouldn’t impact the function run in a negative way.