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EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
ELR 9000 HP Series
3.11
Other applications
3.11.1 Parallel operation in master-slave (MS)
Multiple devices of same kind and model can be connected in parallel in order to create a system with higher total
current and hence higher power. This can be done using the standard models with display and control panel or
the new slave models (ELR 9000 HP Slave, available from mid 2018). These models are intended to run as slave
only and thus have no display and cheaper. Only disadvantage: the slave models are only available as 15 kW
versions, so they only match the 15 kW standard models.
For parallel operation in master-slave mode the units are usually connected with their DCinputs, their Share bus
and their master-slave bus, which is a digital bus that makes the system work as one big unit regarding adjusted
values, actual values and status.
The Share bus is intended to balance the units dynamically in their input current when running CV mode, especially
if the master unit runs a function like sine wave etc. In order for this bus to work correctly, at least the DC minus
poles of all units have to be connected, because DC minus is the reference for the Share bus.
Principle view (without source connected):
Share Bus connection
Master-slave bus
Bus termination
3.11.1.1 Restrictions
Compared to normal operation of a single device, master-slave operation has some limitations:
•
The MS system reacts differently to alarm situations than a single unit (see below in
)
•
Using the Share bus makes the system reacts as dynamically as possible, but it is still not as dynamic as single
unit operation
•
A device which was configured as slave has limited operability (only access to MENU possible)
3.11.1.2 Wiring the DC inputs
The DC input of every unit in the parallel operation is simply connected to the next unit using cables with cross
section according to the maximum current and with short as possible length.
3.11.1.3 Wiring the Share bus
The Share bus is wired from unit to unit with an ideally twisted pair of cables with non-critical cross section. We
recommend to use 0.5 mm² to 1 mm².
• The Share bus is poled. Take care for correct polarity of the wiring!
• In order for the Share bus to work correctly it requires at least to connect all DC minus
inputs of the devices
