User manual

Page 75
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
[e-mail]
EL 9000 B HP Series
3.11 Other applications
3.11.1 Series connection
Series connection is not a permissible operating method for electronic loads and must not be
installed or operated under any circumstances!
3.11.2 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 true master-slave operation, the units have to be connected with their DC
inputs, their master-slave bus and their Share bus.
The master-slave bus is a digital bus and enables the system to work as one big unit regarding adjustment of
values and monitoring the status and values.
The Share bus will dynamically balance the units in their internal current regulation, 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.
3.11.2.1 Restrictions
Compared to normal operation of a single device, master-slave operation has some limitations:
• The MS system reacts differently to alarm situations (see below in 3.11.2.6)
• Using the Share bus makes the system reacts as dynamically as possible, but it is still not as dynamic as single
unit operation
3.11.2.2 Wiring the DC inputs
The DC input of every unit in the parallel operation is connected to the next unit using cables with a cross section
matching maximum current and with short as possible length.
3.11.2.3 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
A max. of 10 units can be connected via Share bus.
3.11.2.4 Wiring and set-up of the master-slave bus
Themaster-slaveconnectorsarebuilt-inandmustrstbeconnectedvianetworkcables(≥CAT3,patchcable)and
thenMScanbeconguredmanually(recommended)orbyremotecontrol.Thefollowingapplies:
• A maximum 10 units can be connected via the bus: 1 master and up to 9 slaves.
• Only connect devices of same kind, i.e. electronic load to electronic load, and of same rating, such as EL 9080-
170 B HP to EL 9080-170 B HP or to EL 9080-170 B 2Q.
• Units at the end of the bus must be terminated (see below)
The master-slave bus (RS485) must not be wired using crossover cables!
Later operation of the MS system implies:
• the master unit displays, or makes available to be read by the remote controller, the sum of the actual values
of all the units
• the range for setting the values of the master is adapted to the total number of units, thus, if e.g. 5 units each with
a power of 2.4 kW are connected together to a 12 kW system, then the master can be set in the range 0...12 kW.