Dc Link Components; Braking Module; Description - Siemens SINAMICS S120 Equipment Manual

DC link components

11.1

Braking Module

11.1.1

Description

A Braking Module (and an external braking resistor) are required for a controlled shutdown of
drives during power failure (e.g. emergency retraction or EMERGENCY STOP Category 1)
or to limit the DC link voltage during temporary regenerative operation when, for example,
the regenerative capability of the Line Module is deactivated or not appropriately
dimensioned.
The Braking Module includes the necessary power electronics together with its control. The
Braking Module is operational, the regenerative energy is dissipated as thermal energy in an
external braking resistor.
Further, the Braking Module can also be used with a braking resistor to quickly discharge the
DC link. The DC link is discharged in a controlled manner via the braking resistor once the
rectifier unit has been switched off and the line-up has been disconnected from the power
supply (e.g. main circuit-breaker, line contactor). The function can be activated via a digital
input on the braking module.
To operate the braking modules, a minimum capacitance is required in the DC link.
Depending on the braking resistor used, this is:
braking resistor 25 kW, DC link capacitance 440 µF;
braking resistor 100 kW, DC link capacitance 440 µF.
The capacitance of the braking modules of 110 µF is included in the total capacitance.
When the braking modules are connected in parallel, the above-mentioned minimum
capacitance must be available for each braking module.
Note
The fast discharge function is used for discharging the capacitors in the DC link after
interruption of the mains supply. This makes sense, for example, when maintenance tasks
are to be performed at the Motor Module and/or motor installation (reduction of the discharge
time). For this purpose, the drive system must be completely disconnected from the supply
and the motors must be in standstill position.
Note
Only the components that are connected to each other via the DC link busbar can be
included in the total capacitance.
The cable between the braking module and the braking resistor is limited to 10 m.
Booksize cold-plate power units
Manual, (GH4), 03.2007, 6SL3097-2AJ00-0BP4
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