Braking Functions Of The Inverter; Comparison Of Electrical Braking Methods - Siemens SINAMICS G120 Operating Instructions Manual

7.9.2

Braking functions of the inverter

A differentiation is made between mechanically braking and electrically braking a motor:
● Mechanical brakes are generally motor holding brakes that are closed when the motor is
● The motor is electrically braked by the inverter. An electrical braking is completely wear-
7.9.2.1

Comparison of 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:
● Grinding disk drives
● Fans
For certain drive applications, the motor can operate in the regenerative mode for longer
periods of time, e.g.:
● Centrifuges
● Hoisting gear and cranes
● Conveyor belts with downward movement of load (vertical or inclined conveyors)
Depending on the Power Module used, the inverter offers the following options to convert the
regenerative power of the motor into heat or to feed it back into the line:
● DC braking (Page 190)
● Compound braking (Page 193)
● Dynamic braking (Page 195)
● Braking with regenerative feedback to the line (Page 197)
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 01/2011, FW 4.4, A5E02299792B AB
at a standstill. Mechanical operating brakes, that are closed while the motor is rotating
are subject to a high wear and are therefore often only used as an emergency brake.
If your motor is equipped with a motor holding brake, then you should use the inverter
functions to control this motor holding brake, see Section Motor holding brake
(Page 198).
free. Generally, a motor is switched off at standstill in order to save energy and so that
the motor temperature is not unnecessarily increased.
for Power Module PM240, PM250 and PM260
for Power Module PM240
for Power Module PM240
for Power Module PM250 and 260
7.9 Application-specific functions
Functions
187