Braking Resistors; Description; Safety Information - Siemens SINAMICS S120 Equipment Manual

DC link components
4.2 Chassis
4.2.2

Braking resistors

4.2.2.1

Description

The braking resistor is used to reduce the excess DC link energy in regenerative operation.
The braking resistor is connected to the Braking Module. The braking resistor is mounted
outside the cabinet or switchgear room. This means that the resulting heat loss around the
Power Module can be dissipated - and cooling costs/equipment reduced.
Resistors with rated powers of 25 kW and 50 kW are available.
Braking resistors can be used on Power Modules with a voltage range. This is the reason
that the voltage can be changed by setting the response thresholds at the Braking Module to
reduce the voltage stress on the motor and Power Module.
A temperature protection switch monitors the braking resistor for overtemperature and issues
a signal on a floating contact if the limit value is exceeded.
4.2.2.2

Safety information

Caution
A cooling clearance of 200 m must be maintained on all sides of the component (with
ventilation meshes).
Danger
The braking resistor cables must be laid in such a way that they are short-circuit and ground-
fault proof!
Caution
The connecting cables to the Braking Module in the Power Module must be kept as short as
possible (max. 50 m).
4-20
Equipment Manual AC Drive
Manual, (GH6), 03/2006 Edition, 6SL3097-2AL00-0BP0