Armature Short-Circuit Braking, Dc Braking - Siemens SINAMICS S120 Function Manual

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Basic functions

6.11 Armature short-circuit braking, DC braking

Armature short-circuit braking, DC braking

The "Armature short-circuit braking" and "DC braking" functions can be set using parameters

p1231[0...n]. The current status of the armature short-circuit braking or the DC braking can

be seen in r1239.

Armature short-circuit braking

Using this function, you can brake permanent-magnet synchronous motors. The stator

windings of synchronous motors are then short-circuited. For a rotating synchronous motor,

a current flows that brakes the motor.

Armature short-circuit braking is preferably used in the following cases:

● If braking is to be performed without feedback

● If braking is to be performed when the power fails

● If an infeed unit is used that is not capable of feedback

● If with orientation loss (e.g. with encoder errors), the motor should still be braked

You can switch the armature short-circuit braking internally via the Motor Module or

externally using a contactor circuit with braking resistors.

The advantage of armature short-circuit braking over a mechanical brake is the response

time of the internal armature short-circuit braking with just a few milliseconds. The response

time of a mechanical brake is about 40 ms. For external armature short-circuit braking, the

slowness of the switching contactor results in a response time of over 60 ms.

Using this function, you can brake induction motors down to standstill. With DC braking, a

DC current is impressed in the stator windings of the induction motor.

DC braking is preferred in the event of danger:

● If it is not possible to ramp-down the drive in a controlled fashion

● If an infeed unit not capable of feedback is used

● If no braking resistor is used

Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3

Drive functions