Engineering Guide CDA3000
3-83
3 Selection of inverter module
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Project planning notes for DC network operation
Subject Project planning notes
Mains connection
of the inverter
modules
• All inverter modules must be operated with a line choke. The line
choke limits the mains current and provides current/power sym-
metry of the inverter input circuits.
• For more information on this subject refer to section 3.2.
Mains fuse (F1)
with signal contact
• By the use of mains fuses with signal contact the “Mains power
supply failure” fault can be responded to by shutting down the
entire DC network. As a result the remaining inverter modules in
the DC network are not overloaded.
Mains power con-
nection condition
• It must be ensured that all inverter modules are connected simul-
taneously (K1) to the mains power.
DC link connection • Make short cable connections to the common DC-link center
point.
• Use cable cross-section corresponding to mains power cable
cross section (see Operation Manual and section 3.2).
• Select DC-link fuses corresponding to the cable cross-section and
local regulations. The fuses protect the cable.
• The DC fuses can be omitted if the cable cross-section used to
wire the DC network is at least as large as the mains power cable
cross-section of the highest-powered inverter module in the net-
work.
Tip: Where the DC network comprises only two inverter
modules only one fuse pair (F3/4) is sufficient for pro-
tection purposes.
If the DC network is connected to the mains - while an
inverter module has an internal short-circuit on the DC
link - the defective inverter module is automatically
isolated from the DC network by its PTC precharging
circuit. All other inverter modules can continue in oper-
ation;
see Figure 3.37.
Table 3.38 Project planning notes for DC network operation
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