11/03 Electrical Installation
SINAMICS G150
Operating Manual
4-37
Duty Cycles
10 20 30 40 50 60 70 80 90 100 110 120 130
0.25
0.50
0.75
1.00
1.25
1.50
P/P
20
t/s
P
15
P
20
P
40
P
DB
P
DB
= Continuous braking power
P
15
= 5 x P
DB
= Power permissible every 90s for 15s
P
20
= 4 x P
DB
= Power permissible every 90s for 20s
P
40
= 2 x P
DB
= Power permissible every 90s for 40s
Fig. 4-10 Duty cycles for the braking resistors
Threshold Switch
The response threshold at which the braking unit is activated and the DC link
voltage generated during braking are specified in the following table.
WARNING
The threshold switch must only be used when the cabinet unit is switched off and
the DC link capacitors are discharged.
Table 4-29 Response thresholds for the braking units
Rated voltage Response
threshold
Switch
position
Comments
774 V 1
380 V -480 V
673 V 2
774 V is the default factory setting. With supply voltages of
between 380 V and 400 V, the response threshold can be set
to 673 V to reduce the voltage stress on the motor and
converter. This does, however, reduce the possible peak
power (P
15
) with the square of the voltage (677/774)² = 0.75.
The possible peak power is, therefore, max. 75 % of P
15
.
660 V -690 V 1158 V 1
1158 V is the default factory setting. With a supply voltage of
660 V, the response threshold can be set to 1070 V to reduce
the voltage stress on the motor and converter. This does,
however, reduce the possible peak power (P
15
) with the
square of the voltage (1070/1158)² = 0.85.
The possible peak power is, therefore, max. 85 % of P
15
.
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