64
EN
Operating Guide
PSI 8000 2U Series
Date: 28-06-2012
10. Special characteristics
10.1 Remote sense
Remote sense operation is used to compensate voltage drops
along the cables between the power supply and the load. Becau-
se this is limited to a certain level, it is recommended to match
the cross section of the cables to the output current and thus
minimise the voltage drop. On the rear panel of the device there
is a terminal
System Bus
where the sense cables are wired
with correct polarity. The power supply will detect the external
sense automatically and compensate the output voltage by
the actual voltage at the load instead of the output. The output
voltage will be raised by the value of the voltage drop between
power supply and load. See figure 9 as an example.
Maximum compensation: see „2. Technical specifications“.
10.2 Connecting different types of loads
Different types of loads, such as ohmic loads (lamp, resistor),
electronic loads or inductive loads (motor) behave differently
and can retroact to the power supply. For example, motors
can induce a countervoltage which may cause the overvoltage
protection of the power supply to shut off the output.
Electronic loads have regulator circuits for voltage, current and
power that can counteract to the ones of the power supply and
may result in increased output ripple or other, unwanted side
effects. Ohmic loads are nearly 100% neutral. It is recommen-
ded to consider the load situation when planning applications.
10.3 Mains undervoltage or overvoltage
The device features an active rectification with PFC and a wide
range input. This means, it can be operated at input voltages
of approx. 90V...264V, respectively 180V...264V. Input voltages
below 90V resp. 180V are considered as blackout, respectively
as complete switch-off and will store the last condition, as well
as switch off the power output.
Attention!
Permanent input undervoltage or overvoltage must be
avoided!
Note
Models with 1500W nominal power will automatically derate
the output power down to 1000W at input voltages below
approx.150V. At models with 3000W nominal power the de-
rated output power will be 2000W, starting at around 205V.
This condition is not indicated by the device and the power set
value of models with adjustable power is not altered. Derating
can only be recognized by the user from the actual values of
voltage and current.
Using the power supply
11. Other applications
11.1 Functions of terminal System Bus
The 8pole terminal
System Bus
is located on the rear and is
used to connect cables for remote sense or to wire multiple
devices for series or parallel connection.
Pin assignment:
1 : Sense +
2 : Sense -
3 : Master output Current
4 : Master output Voltage
5 : Slave input Current
6 : Slave input Voltage
7 : Share Bus
8 : Ground
Attention!
The functions of pins 3-8, as described in the subsequent
paragraphs, are only available at models from 1000W
output power.
11.1.1 Series connection in Master-Slave mode
Note
Only available with devices from 1kW nominal power. Not
available for the 720V model.
For a series connection, it is recommended to use only devices
with identical output current, else the unit with the lowest nominal
output current will define the maximum current of the system.
One unit is always the master of the next unit, which becomes
slave, and so on. When connecting more than two units, it
is recommended to consider one certain unit as master and
any other as slave. The slave(s) are controlled by the master
via the slave input pins 3 and 4 of the terminal
System Bus
.
Voltage and current can be controlled simultaneously, but also
seperately.
For an example wiring see figure 10. Voltage and current are
here given by the master. In case only one of both, voltage or
current, is going to be controlled, the other set value should
be set to 100%.
In order to control the whole system remotely, it is sufficient to
control the master via its analog or digital interface. When rea-
ding actual values, the current monitor value will represent the
overall system current, but the voltage monitor only the output
voltage of the master.
Figure 9
