20
Only converters that are connected to the main supply, are used for the power limit
calculations. The power correction factor, k, for each combination can be found from
Table 1. When several converters are connected to the main supply, the least efficient
power correction factor is chosen from table 1, i.e. the smallest factor. See Example1
and Example2.
When the charging circuits of the converters are different, this connection is not always
allowed. The table below shows when the connection cannot be used.
ACS850 power correction factors
Frame size A, B C, D E0 or E G
A, B k=0.8 No k=0.6 C k=0.6 C
C, D No k=0.5 No No
E0 or E k=0.6 C No k=0.7 k=0.6
G k=0.6 C No k=0.6 k=0.7
No: Do not connect the supply of the smaller converter. The converters have different types of input
chokes. Frame sizes C and D have DC chokes and frame sizes E0-G have AC chokes.
C: If both converters are connected to the main supply, the DC links must be connected together via a
contactor because the converters have different charging circuits. The DC contactors are switched on after
all of the DC links are charged and the converters are in the READY state.
Note: The P
rec.ave
value is higher if the smallest converter is not connected to the main
supply.
Example 1
The DC buses of three converters ACS850-04-08A0-5, 4.7 kW, (A); ACS850-04-035A-
5, 20.5 kW, (C) and ACS850-04-035A-5, 20.5 kW, (C) are connected together. The
input terminals of the 3 kW converter are left unconnected. k = 0.5 when two frame C´s
are connected to the main supply, therefore P
rec,ave is
P
rec,ave = 20.5kW + 0.5 · 20.5kW = 30.75 kW
Example 2
The DC buses of three converters ACS850-04-103A-5, 61 kW, (E0); ACS850-04-202A-
5, 119.3 kW, (E) and ACS850-04-521A-5, 315.3 kW, (G) are connected together. All
three converters are connected to the main supply. According to Table 1, k = 0.7 when
E0 and E are connected to the main supply and k = 0.6 when E and G are connected
to the main supply. The lowest factor is used in the calculations, i.e. k = 0.6, therefore
P
rec.ave = 315.3 kW + 0.6 ·119.3 kW + 0.6 · 61 kW = 423.5 kW
Common DC configurations
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