65
Operating Guide
PSI 8000 2U Series
EN
Date: 28-06-2012
Using the power supply
In order to get accurate readings, either the actual voltage is
multiplied by the number of unit in the series connection (only
applicable if all are same type) or all units will have to be read
seperately.
There are some restrictions and rules to consider because of
safety and isolation reasons:
•
The negative DC output pole of no unit in the series
connection may be raised to a potential >300V against
ground (PE)!
•
The Share bus must not be wired!
•
The grounds (AGND, DGND) of the analog interfaces of
the units must not be wired to each other!
•
Remote sense must not be wired!
Example: Two identical units with 360V nominal voltage, for
example PSI 8360-15 2U, shall be connected in series. When
calculating, the total voltage of that series connection could go
up to 720V. Looking at the resulting potentials on the negative
outputs of the units, the 2nd unit‘s negative DC pole could be
raised to 360V. This is not permitted! So the lower unit has to
be limited to a certain maximum. The figure below clarifies that
the resulting total voltage would be 660V:
11.1.2 Parallel connection with Share Bus
Note
Only available with devices from 1kW nominal power!
Attention!
Only units of the same type (voltage and current) must be
used in parallel operation. See figure 11 for an example.
Attention!
Parallel connection with units different to 2U series, which
also feature a Share bus, is not allowed! Only exception:
two quadrants operation with an electronic load.
Share bus operation is used to gain a symmetric load current
distribution when running multiple units in parallel connection.
Follwing connections are required: connect all (+) DC outputs
of the units to each other and all (–) DC outputs to each other.
Pin 7 (Share Bus) and pin 8 (Ground) of terminal
System Bus
of all units are also con nected in parallel. In case remote sense
is also required, all Sense+ and all Sense - inputs are connected
in parallel and also with the load.
Important
: in this operation mode, the unit with the
lowest
output
voltage controls and defines the output voltage of the whole
parallel connection. It means, any unit of the system could be
in charge. Thus it is recommended to pick a unit that is used to
control the whole system, while the set value of voltage for the
remaining units is set to the required minimum. Voltage and po-
wer set value could be set to 100% or, if not desired, set to equal
values on every unit so that the total results in what‘s required.
Figure 10. Series connection in Master-Slave
