Central Braking Modules; Design - Siemens SINAMICS G130 Engineering Manual

SINAMICS S120 Cabinet Modules
Engineering Information
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Central Braking Modules

Design

Central Braking Modules are placed in a central position within the drive configuration built of S120 Cabinet Modules.
With their high braking power they limit the DC link voltage if regenerative energy occurs in the DC link, which cannot
be fed back into the supply system. This means that fault trips of the Motor Modules caused by DC link overvoltage
can be avoided. Also a fast deceleraton of the drives becomes possible.
If the DC link voltage of the DC busbar exceeds a certain limit in regenerative operation, an
externally installed braking resistor is activated, which prevents a further increase of the DC
link voltage. As a result, the regenerative energy is converted into heat.
The activation of the braking resistor is done by the Braking Unit, which is installed in the
Cabinet Module. Central Braking Modules are an alternative to the optional Braking
Modules (Option L61, L62 resp. L64, L65), particularly if very high braking power is
required in a drive configuration. Central Braking Modules operate completely
independently and only require a connection to the DC link. An external auxiliary supply
voltage is not necessary.
The Braking Units can be used with all line supply types. The response threshold of the
Braking Modules, i.e. the DC link voltage where they start to operate, can be adapted to the
requirements on site using a switch in the Braking Module.
The units have an integrated temperature monitor. An internal fan provided as a standard
supports the cooling of the Power Unit. Switching on and off of the fan is temperature-
controlled. Thus continuous operation of the fan is avoided. The permissible ambient
temperature for operation with rated power is 0°C - 40º C. At higher temperatures between
40ºC and 50ºC a power derating has to be taken into account in accordance with the
formula:
P
The installation altitude can be up to 2000 m above sea level. For altitudes higher than
1000 m, a power derating has to be taken into account, which is 1.5% per 100 m.
In addition to the temperature monitoring function, other protection measures are
implemented such as overcurrent and overloads protection.
The Braking Units are also equipped with LEDs for optical indication of fault conditions and
a control output, which is activated in case of a fault. The Braking Unit can be externally
blocked using a control input.
Example configuration of a Central Braking Module
Example configuration of a Central Braking Module
In most applications, the Central Braking Modules are only used for occasional braking operation, but it is possible to
use them for continuous braking operation. In this case, the load duty cycles shown in the following diagram must be
taken into account.
SINAMICS Engineering Manual – May 2008
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