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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
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Loss of connection to any slave will result in shutdown of all DC inputs, as a safety measure, and the master
will report this situation in the display with a pop-up “Master-slave safety mode”. Then the MS system has to be
re-initialised, either with or without re-establishing connection to the disconnected unit(s) before.
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All units, even the slaves, can be externally shut down on the DC inputs using the pin REM-SB of the analog
interface. This can be used as some kind of emergency off, where usually a contact (maker or breaker) is wired
to this pin on all units in parallel.
3.11.1.6 Alarms and other problem situations
Master-slave operation, due to the connection of multiple units and their interaction, can cause additional problem
situations which do not occur when operating individual units. For such occurrences the following regulations have
been defined:
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Generally, if the master loses connection to any slave, it will generate an MSP (master-slave protection) alarm,
pop up a message on the screen and switch off its DC input. The slaves will fall back to single operation mode,
but also switch off their DC input. The MSP alarm can be deleted by either initialising the master-slave system
again. This can be done either in the MSP alarm pop-up screen or in the MENU of the master or via remote
control. Alternatively, the alarm is also cleared by deactivating master-slave on the master unit
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If one or more slave units are switched off on the AC side (power switch, supply undervoltage) and come back
later, they’re not automatically initialised and included again in the MS system. Then the init has to be repeated.
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If the DC input of the master unit is switched off due to a defect or overheating, then the total master-slave system
can take no input power and the DC input of all slaves is automatically switched off, too.
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If accidentally multiple or no units are defined as master the master-slave system cannot be initialised.
In situations where one or multiple units generate a device alarm like OV, PF or OT following applies:
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Any alarm of a slave is indicated on the slave’s display and on the master’s display
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If multiple alarms happen simultaneously, the master only indicates the most recent one. In this case, the particu-
lar alarms can be read from the slave units displays. This also applies to remote control or remote supervision,
because the master can only report the most recent alarm.
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All units in the MS system supervise their own values regarding overvoltage, overcurrent and overpower and
in case of alarm they report the alarm to the master. In situations where the current is probably not balanced
between the units, it can occur that one unit generates an OC alarm though the global OC limit of the MS system
was not reached. The same can occur with the OP alarm.
3.11.1.7 Important to know
In case one or several units of a parallel system are not going to be used and remain switched
off, depending on the number of active units and the dynamics of the operation it may become
necessary to disconnect the inactive units from the Share bus, because even when not powered
the units can have a negative impact on the Share bus due to their impedance.
3.11.2 Series connection
Series connection is not a permissible operating method for electronic loads and must not be
installed or operated under any circumstances!
