Braking Functions Of The Converter; Electrical Braking Methods; Dc Braking - Siemens Sinamics G120P Operating Instructions Manual

Functions
7.7 Application-specific functions
7.7.3

Braking functions of the converter

7.7.3.1

Electrical braking methods

Regenerative power
If an induction motor electrically brakes the connected load and the mechanical power
exceeds the electrical losses, then it operates as a generator. The motor converts
mechanical power into electrical power.
Examples of applications, in which regenerative operation briefly occurs, include:
● Fans that in no-load operation turn backwards because of a draft must be braked before
the start up.
For certain applications, the motor can operate in the regenerative mode for longer periods
of time.
The inverter offers the following options to convert the regenerative power of the motor into
heat:
● DC braking (Page 380)
● Dynamic braking (Page 383)
A comparison with the main features of the individual braking functions is listed in the
following paragraphs.
7.7.3.2

DC braking

DC braking is used for applications, where the motor can be more quickly braked by
impressing a DC current than along a braking ramp.
Function
Danger to life due to fire caused by overheating as the result of thermal motor overload
The motor can overheat if it is braked for long periods of time or frequently using DC
braking. This may damage the motor and even cause fire, resulting in danger to life.
• Monitor the motor temperature.
• If the motor gets too hot during operation you must select another braking method or
With DC braking, the inverter outputs an internal OFF2 command for the time that it takes to
de-energize the motor p0347 - and then impresses the braking current for the duration of the
DC braking.
380
WARNING
give the motor more time to cool down.
Inverter cabinet units
Operating Instructions, 12/2014, A5E32923362A