Dual-Frequency Braking Limitations - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

8.9.3

Dual-Frequency Braking Limitations

Limitations of DFB
The drive output current plus the braking current must not exceed the current capability of the
cells in the drive. Hence the braking torque is limited in the drive, it is greatest at slow speed and
smallest at high speed. The typical braking torque that can be expected with DFB is illustrated
below.
Figure 8-5
With high efficiency and inverter duty motors, the braking torque that can be achieved with DFB
is lower than the values shown in the figure above.
Contact Siemens customer service with the motor-related data listed below to determine the
braking torque capability with a higher efficiency motor. Information on critical frequencies will
allow a selection for the torque pulsation frequency.
Table 8-1
Rated HP
Rated frequency
Half-load efficiency
Half-load power factor
Locked-rotor torque
Pull-out torque
NXGPro+ Control Manual
Operating Manual, A5E50491925A
Braking torque with DFB for a typical motor
Motor related data
Advanced Operating Functions
8.9 Dual-Frequency Braking
Rated Voltage
Full-load speed
Full-load efficiency
Full-load power factor
Locked-rotor current
Critical frequencies of the mechanical system
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