Single Inverter; Operation In Parallel - Eltek Valere PWS Series User Manual

DC/AC Inverter
PWS series
User Manual
Page 14 (24)
Connect the input, output and signalling wires according to section 2.5 "Electrical connectors". Wires in
accordance with VDE 0100 or equal standard are to be used. To decrease voltage losses on cables the
usage of larger wire cross sections as specified is recommended. For instance, a high voltage loss on
battery wires can decrease the backup time.
Following installation rules should be observed:

3.2.1 Single inverter

1. check the system wiring ( polarity of DC- supply line )
2. check that the inverter is switched off
3. connect DC input with open DC busbar fuses
4. connect AC loads
5. close the DC busbar fuses
6. switch on the unit with front side switch S1. The rear side switch S2
7. switch on the load
*
REMARK: For more information about switch S2, see section 3.6.

3.2.2 Operation in parallel

REMARK: For parallel operation of PWS inverters it is necessary to use parallel operation chokes at the
outputs of the inverters as shown in figure 1+2). The article codes of the parallel operation chokes are
listed in section 2.3 "Available options".
1. make shure that the inverters to be paralleled are identical in type.
2. check the system wiring (polarity of DC- supply line, synchronous bus)
3. check that the inverters are switched off
4. connect DC input with open DC busbar fuses
5. check the wiring between the inverters (synchronization wires)
6. connect AC loads
7. close DC busbar fuses
8. switch on the units with front side switches (rear side switch S2 in position "0" for remote switch-
on function in combination with a static bypass switch UNB).
9. switch on the load
One of the paralleled inverters operates as master and synchronizes the other inverters to a given
frequency.
Note: The unit which first of all feeds in is the master. If the master unit fails or is switched off, another
unit overtakes the master function.
If paralleled inverters operate in combination with a static bypass switch (UNB), the UNB automatically
is the master. The connected inverters are synchronized by the UNB via the control wire SYNC-STAT.
For a faultless function it is important that the wiring between the inverters (and static bypass switch)
is correct.
The inverters connect themselves to the AC output (over an internal output-side contactor) not till
then the output voltage reaches the nominal value.
REMARK: Due to the connected parallel operation chokes in combination with the resistance of the
wiring the short circuit detection of the units will be affected.
For this application, it is recommended to check individually the short circuit behavior of the system.
Due to the voltage losses at the inductance of the parallel operation choke, the voltage deviation value
exceeds the specified data of the data sheet of the PWS.
ELTEK VALERE INDUSTRIAL ©2008
*
must be in position "I".
UM_PWS_E_R1.2