Series Connection; Operation As Battery Charger - Elektro-Automatik PS 9000 1U Betriebsanleitung

3.9.1.5 Alarms and other problem situations
Parallel operation, due to the connection of multiple units and their interaction, can cause additional problem situ-
ations which do not occur when operating individual units. For such occurrences the following regulations have
been defined:
• If one or more slave units are switched off on the AC side (power switch, supply undervoltage) and come back
later, they're automatically included again in the system. The remaining units will continue to work without inter-
ruption, but the entire system will provide less power
• If the DC output of the master unit is switched off due to a defect or overheating, then the total parallel system
can provide no output power
• If accidentally multiple or no units are defined as master the Share Bus parallel system cannot be initialised
In situations where one or multiple units generate a device alarm like OV, PF or OT following applies:
• Any alarm of a slave is indicated on the slave's display only
3.9.2

Series connection

Series connection of two or multiple devices is basically possible. But for reasons of safety and isolation, some
restrictions apply:
• Both, negative (DC-) and positive (DC+) output poles, are coupled to PE via type X capacitors
• None DC minus pole of any unit in the series connection must have a potential of >400 V
against ground (PE)!
• The Share Bus must not be wired and used!
• Remote sensing must not be used!
• Series connection is only allowed with devices of the same kind and model, i.e. power supply
with power supply, like for example PS 9080-100 1U with PS 9080-100 1U or similar models
like PS/PSI 9080-120 2U
Series connection is not supported by the software and hardware of the device. It means, all units have to controlled
separately regarding set values and DC output status, whether it is manual control or digital remote control. In
remote control, an almost synchronous control can be achieved by using the Ethernet ports and sending message
as broadcast, so they address multiple units at once.
The figure below depicts the exemplary series connection of three identical devices with 200 V nominal output
voltage and the maximum potential shift of any DC- output against PE:
3.9.3

Operation as battery charger

A power supply can be used as a battery charger, but with some restrictions, because it misses a battery supervi-
sion and a physical separation from the load in form of a relay or contactor, which is featured with some real battery
chargers as a protection.
Following has to be considered:
• No false polarity protection inside! Connecting a battery with false polarity will damage the power supply severely,
even if it is not powered.
• All models of this series have an internal circuit, i.e. base load, for faster discharge of voltage when switching the
DC output off or ramping voltage down. This base load would, more or less slowly, discharge the battery while
the DC output is switched off, means while it is not charging. This would, however, not occur when the power
supply is not powered at all. It is thus recommended to leave the DC output switched on as long as the battery
is connected (equals to trickle charge) and only switch if off for connecting/disconnecting a battery.
EA Elektro-Automatik GmbH
Helmholtzstr. 31-33 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
PS 9000 1U Series
www.elektroautomatik.de
ea1974@elektroautomatik.de
Page 47