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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
PSB 9000 3U Series
3.12
Other applications
3.12.1 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. For parallel operation in master-slave mode the units are usually connected with
their DC terminals, 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 voltage on the DC terminal, i.e. in CV mode,
especially if the master unit runs a dynamic function. 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:
Share Bus connection
Master-slave bus
Bus termination
3.12.1.1 Restrictions
Compared to normal operation of a single device, master-slave operation has some
restrictions
:
•
The MS system reacts partly different in alarm situations (see below in
•
Using the Share bus makes the system react as dynamic as possible, but it is still not as dynamic as single unit
operation
•
Connection to identical models from other series is not supported, the master would not initialise them
3.12.1.2 Wiring the DC terminals
The DC terminal of every unit in the parallel operation is connected with correct polarity to the next unit, using
cables or copper bars with a cross section according to the total system current and with short as possible length.
3.12.1.3 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 1.0 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
terminals of the devices
• The Share bus connection between multiple PSB 9000 units running in parallel is abso-
lutely required, because it defines the operation mode (source/sink) for the slave units
