Siemens SINAMICS S120 Manual page 250

Cabinet Modules
5.7 Central Braking Modules
5.7.7 Braking resistor
5.7.7.1 Description
The regenerative energy of the drive line-up is dissipated via the braking resistor. The
braking resistor is connected to a Braking Module. The braking resistor is positioned outside
the cabinet or switchgear room. This enables the resulting heat loss to be dissipated, thereby
reducing the amount of air conditioning required.
A thermostat monitors the braking resistor for overheating and, if the limit value is exceeded,
it is signaled via a floating contact. The tripping temperature is 120 °C; this corresponds to a
surface temperature on the resistor elements of approximately 400 °C.
Only one braking resistor may be connected to a Central Braking Module.
The power of the braking resistors is matched to the rated braking power of the Central
Braking Modules; however, operation is restricted to a reduced duty cycle of 15 seconds
every 20 minutes.
Connecting-up the thermostat
The thermostat contact must be connected on the plant side so that the signal can be
evaluated in the Control Unit or in a higher-level controller; see the section titled
"Configuring the overtemperature checkback signal".
5.7.7.2 Safety information
Hot surfaces
The surface temperature of the braking resistors may exceed 80 °C.
NOTICE
Maintain ventilation clearances
A cooling clearance of 200 mm must be maintained on all sides of the component (with
ventilation grilles).
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WARNING
CAUTION
Cabinet Modules
Manual, 03/2013, A5E03263538A