Siemens SIMOVERT MASTERDRIVES Manual page 879

Engineering Information
11.8 Selection of other components
Line fuses
11-22
The mean braking power is calculated as follows:
P
Mot v A
∑
=
P
br mean
+
P P
Mot v A Mot v E
2
T Cycle time
Only negative motor outputs are evaluated. When calculating the mean
motor output, it must be borne in mind that the initial value and the final
value of the motor speed do not have different signs. An interpolation
point must therefore exist for every zero passage.
If several inverters are connected to one rectifier unit, the mean value is
calculated by adding together the individual mean values for the
inverters.
The selection tables in Catalog DA65.11 are used to make a list of the
other components needed on the rectifier side and on the load side.
Rectifier side
Line fuses
Line switch
Line contactor
Line reactor
Line filter
Table 11-1 Selection of other components
Line fuses, or circuit-breakers in the lower output range, are generally
always necessary. In addition to line protection, fuses with gR
characteristics also protect semiconductors (rectifier). Fuses with gL
characteristics or circuit-breakers are only for line protection; in the
event of a fault in the rectifier or in the DC link, the semiconductors of
the rectifier are not protected. Fuses with gL characterstics or circuit-
breakers are therefore appropriate if units have to be replaced in the
event of a fault. If repairs have to be carried out locally, e.g. for large
outputs, the use of fuses with gR characteristics is recommended.
+
P
Mot v E
⋅ ∆
t
i
2
⋅ η
Mot
T
Mean motor braking power in time segment ∆ t
(A: initial value, E: final value)
6SE7087-6QX70 (Version AE)
Compendium Motion Control
06.2005
⋅ η
Inv
Load side
Output reactor
Siemens AG
SIMOVERT MASTERDRIVES
i