Nord Drivesystems SK 510P - Figure 4: Illustration of a DC-Coupling

2 Assembly and installation
BU 0600 en-2319 43
M
3~
PE U V W +B -B -DC
PE L3 L2 L1
L1 / L
L2 / N
L3 / -
PE
M
3~
PE U V W +B -B -DC
PE L3 L2 L1
Coupling if
FIs ready
Ready message
from all FIs
U1
U2
Figure 4: Illustration of a DC-coupling
1 The link circuits of the individual frequency inverters must be protected with suitable fuses.
2 NOTICE! Ensure that the coupling is only made after readiness is reported. Otherwise, there is
a danger that all the frequency inverters will be charged by a single one.
3 Ensure that the coupling is disconnected as soon as one of the devices is no longer ready for
operation.
4 For a high availability a braking resistor must be used. If different sizes of frequency inverters
are used, the braking resistor must be connected to the larger of the two frequency inverters.
5 If devices with the same rating (identical type) are coupled, and the same mains impedances
are in effect (identical lengths of cable to the mains rail), the frequency inverters may be
operated without mains chokes. Otherwise a mains choke must be installed in the mains cable
of each frequency inverter.