User Manual

Page 38
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
3.3.6 Sink-source mode switching
The switchover between sink and source mode happens automatically and only depends on the device’s voltage
setting and actual value on the DC terminal or the remote sense connector, if in use.
It means, that when connecting an external voltage source to the DC terminal, only the voltage set value deter-
mines the operation mode. When connecting a load which can’t generate a voltage, only source mode can be run.
Rules for applications with external voltage source connected:
• If the voltage set value is higher than the actual voltage of the external source, the device will run in source mode
• If the voltage set value is lower, it will run in sink mode
To run one of both modes explicitly, i.e. without automatic switchover, it would require following:
• for “source only mode” adjust the current set value for the sink to 0
• for “sink only mode” adjust the voltage set value to 0
3.3.7 Dynamic characteristics and stability criteria
When working in sink mode, the device becomes an electronic load which is characterised by short rise and fall
times of the current, which are achieved by a high bandwidth of the internal regulation circuit.
In case of testing sources with own regulation circuits at the load, like for example power supplies, a regulation
instability may occur. This instability is caused if the complete system (feeding source and electronic load) has too
littlephaseandgainmarginatcertainfrequencies.180°phaseshiftat>0dBamplicationfullstheconditionfor
an oscillation and results in instability. The same can occur when using sources without own regulation circuit (eg.
batteries), if the connection cables are highly inductive or inductive-capacitive.
The instability isn’t caused by a malfunction of the load, but by the behavior of the complete system. An improvement
of the phase and gain margin can solve this. In practice, a capacity is directly connected to the DC input, perhaps
alternatively to the remote sense input, if connected to the source. The value to achieve the expected result isn’t
denedandhastobefoundout.Werecommend:
60/80 V models: 1000uF....4700uF
200/360 V models: 100uF...470uF
500 V model: 47uF...150uF
750 V model: 22uF...100uF