23
where the U
ac
is the line to the line supply voltage. The charging time is generally about
0.3 s (U
dc
> 95% U
dcN
) with the drive modules.
Frame sizes A…D
In frame sizes A-D the charging resistor is in series with the DC capacitors and all DC
buses are charged via their own resistors despite of the main supply connection. The
inrush current remains at an acceptable level, if the maximum number of unconnected
converters per one connected converter is five.
Note: Always connect the biggest converter to the main supply.
Frame sizes E0, E and G
In frame sizes E0, E and G the charging circuit is in parallel with the input bridge. The
charging resistor of the connected converter limits the number of the unconnected
converters. The charging circuit of the connected converter must be able to withstand
the total charging energy E
tot, i.e.
E
rconnected
> E
tot
The charging energy of the DC link capacitors of a single converter is calculated as
follows.
E
rconnected
= charging resistor’s energy pulse withstand of the connected converter
E = 1/2 · C
DC
· (1.35 · U
net
)
2
C
DC
= capacitance of the DC-bus capacitor. See DC link capacitance.
U
net
= actual supply voltage
The total charging energy of the system E
tot is calculated by summing the energies of
single converters.
E
tot
= 1/2 (C
DC1
+…+C
DCn
)1.35 ·U
net
)
2
The energy pulse withstands E
r of the charging circuits are listed in the following table:
Frame size Er / J
E0 1000
E 2000
G 5600
Note: Always connect the biggest converter to the main supply. If the charging circuit
of the biggest converter is not capable of delivering the demanded charging energy,
connect also the next biggest converter to the main supply.
Common DC configurations
To Next Page
Loading...
