User Manual

Page 35
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. Operation and application
3.1 Terms
The device is a combination of a power supply and an electronic load. It can work alternatingly in one of two superior
operation modes which are distinguished from each other in several parts of this document below:
• Source / source mode:
• the device works as a power supply, generating and providing DC voltage to an external DC load
• in this mode, the DC terminal is considered as DC output
• Sink / sink mode:
• the device works as an electronic load, sinking DC energy from an external DC source
• in this mode, the DC terminal is considered as DC input
3.2 Important notes
3.2.1 Personal safety
• In order to guarantee safety when using the device, it’s essential that only persons operate
the device who are fully acquainted and trained in the required safety measures to be taken
when working with dangerous electrical voltages
• For models which can generate a voltage which is dangerous by contact, or is connected to
such, the included DC terminal cover, or an equivalent, must always be used
• Read and follow all safety warnings in section 1.7.1!
3.2.2 Genera
• When running the device in source mode, unloaded operation isn’t considered as a normal op-
eration mode and can thus lead to false measurements, for example when calibrating the device
• The optimal working point of the device is between 50% and 100% voltage and current
• It’s recommended to not run the device below 10% voltage and current, in order to make sure
technical values like ripple and transient times can be met
3.3 Operating modes
Apowersupplyisinternallycontrolledbydi󰀨erentcontrolorregulationcircuits,whichshallbringvoltage,current
and power to the adjusted values and hold them constant, if possible. These circuits follow typical laws of control
systemsengineering,resultingindi󰀨erentoperatingmodes.Everyoperatingmodehasitsowncharacteristics
which is explained below in short form.
3.3.1 Voltage regulation / Constant voltage
Voltage regulation is also called constant voltage operation (CV).
The voltage on the DC terminal of the device is held constant on the adjusted value, unless the current or the
power according to P = U
DC
* I reaches the adjusted current or power limit. In both cases the device will automat-
icallychangetoconstantcurrentorconstantpoweroperation,whateveroccursrst.Thenthevoltagecan’tbe
held constant anymore and will sink (in source mode) or rise (in sink mode) to a value resulting from Ohm’s law.
CV is available for both, sink and source mode, and primarily depends on the relation between voltage set value
and voltage level on the DC terminal. The device will switch between both modes seamless when adjusting voltage.
In source mode, the output voltage in CV mode is equal to the setting while in sink mode the setting must always
be lower than the input voltage in order to have the device draw current.
While the DC power stage is switched on and constant voltage mode is active, the condition “CV mode active”
will be indicated on the graphics display by the abbreviation CV and this message will be passed as a signal to
the analog interface, as well stored as status which can also be read as a status message via digital interface.
3.3.1.1 Transient time after load step (source mode)
For constant voltage mode (CV), the technical date “Transient time after load step” (see 1.8.3)denesatimethat
is required by the internal voltage regulator of the device to settle the voltage (in source mode) after a load step.
Negative load steps, i.e. high load to lower load, will cause the output voltage to overshoot for a short time until
compensated by the voltage regulator.