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Using the power supply
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. Because
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 front panel if the device there is a terminal
Sense where the sense cables are wired to 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.
Maximum compensation: see technical specs in section 2.2.
Figure 8. Wiring remote sense
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 counter voltage 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 ef-
fects. Ohmic loads are nearly 100% neutral. It is recommended
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. 90 V...264 V. Input voltages below 90 V 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 1500 W nominal power will automatically derate
the output power down to 1000 W at input voltages below
approx. 150 V. 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.
62
Date: 02-05-2016
10.4 Switching on or off by standby button
Same behaviour as when switched on or off by power switch. The
last condition is restored or not, according to the setting
ON" in the device setup.
11. Other applications
11.1 Parallel connection
Parallel connection of (ideally) identical units is used to increase
the output current. For a parallel connection, all positive DC out-
puts are connected to each other and all negative DC outputs
to each other.
There are several ways to realise a parallel connection:
a) The units are connected to each other in a kind of master-slave
operation, by wiring the analog interfaces from unit to unit. Also
see „9.4 Example applications". Here the master will control all
slaves or only the next slave, which will be the master of the next
one, etc. The unit which was assigned as master could additionally
be monitored and remote controlled by a digital interface card.
There will be no totals formation on the master.
Advantages: symmetric load distribution, master monitorable,
actual values from the master can be multiplied with the number
of (identical) units, no external analog control unit required
Disadvantages: in case the wiring is done so that one unit is the
master of the next unit and a slave drops out because of an error,
the rest of the chain will no longer provide power output; the same
applies for the whole system, if the master drops out.
b) An external control unit, for a example a PLC, provides the
required analog set values and controls every unit separately. The
unit are only connected in parallel with their DC outputs.
Advantages: better supervision of the single units, if one unit fails
the other will continue to work without interruption (redundancy)
Disadvantages: extra hardware required, long signal lines which
will be susceptible for glitches and HF interference, symmetric
load distribution not guaranteed, no master-slave
11.2 Series connection
A series connection of power supplies with identical or different
nominal output voltage and (ideally) identical nominal output cur-
rent is used to gain a higher total voltage.
In this connection, the unit with the smallest output current will
determine the maximum current of the whole setup.
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 con-
nection may be raised to a potential >300 V against ground
(PE)!
• The grounds (AGND, DGND) of the analog interfaces of the
units must not be wired to each other!
• Remote sense must not be wired!
© 2006, Elektro-Automatik GmbH & Co. KG
Irrtümer und Änderungen vorbehalten
Example: Two identical units with 360 V nominal voltage, for
example PSI 8360-10 T, shall be connected in series. When
calculating, the total voltage of that series connection could go
up to 720 V. Looking at the resulting potentials on the negative
outputs of the units, the 2nd unit's negative DC pole could be
raised to 360 V. 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 660 V:
EN
„Power
Operating Guide
PSI 8000 T Series
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