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EPS Stromversorgung GmbH
Alter Postweg 101 • 86159 Augsburg
Germany
Fon: +49 821 / 570451-0
Fax: +49 821 / 570451-25
www.eps-germany.de
PSI 9000 2U Series
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 and on the master’s display
•
If multiple alarms happen simultaneously, the master only indicates the most recent one. In this case, the par-
ticular alarms can be read from the slave units displays or via digital interface during remote control or remote
supervision.
•
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 OCP alarm though the global OCP limit of the MS
system was not reached. The same can occur with the OPP 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 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,
limiting the max. allowed potential shift (see technical specs for values)
•
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/PSI 9080-60 2U with PSI 9080-60 2U or PS 9080-60 2U
Series connection in Master-Slave mode is not supported. It means, all units have to controlled separately regard-
ing set values and DC output status, whether it is manual control or digital remote control.
According to the limit of the potential shift that comes with series connection, units with a certain nominal output
voltage must not be connected in series at all. For example, the 750 V, because there the DC minus is only isolated
up to ±400 V DC against PE. On the opposite, two 360 V units are allowed to be connected in series.
The analog interfaces of units in series connection are allowed to be wired in parallel, because they are galvanically
isolated from the device and the DC output. The grounds (AGND, DGND) on the analog interface are also allowed
to be directly connected to PE, like it automatically happens when controlling and directly connecting it to a PC.
3.11.3 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.
