Siemens Sinamics S120M, Equipment Manual

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5.11 Motor holding brake
5.11.1 Description
The holding brake is used to clamp the motor shaft when the motor is at a standstill. It is not a
working brake that is used to brake a motor that is still rotating.
Restricted Emergency Stop operation is permissible. Up to 2000 braking operations can be
executed with three times the rotor moment of inertia as external moment of inertia from a
speed of 3000 rpm, without the brake being subject to an inadmissible amount of wear. The
specific highest switching work for each emergency braking operation may not be exceeded.
NOTICE
Wear to the brakes due to switching times which are too long or too frequent
Excessive wear means that the braking function can no longer be guaranteed. Exceeding the
emergency stop conditions specified above or briefly accelerating the motor repeatedly
against a brake that is still closed leads to premature wear.
● Take into account the switching times of the brakes for drive control or release purposes.
Note
Length of the S120M
The length of the S120M does not depend on whether there is a holding brake.
The holding brake is a brake equipped with permanent magnets. The magnetic field of the
permanent magnets results in a pulling force on the brake armature disk. This means that in the
no-current condition, the brake is closed and the motor shaft is held.
When the rated voltage is connected to the brake, the solenoid – through which current flows
– establishes an opposing field. As a result, the force of the permanent magnets is neutralized
and the brake opens without residual torque on account of the spring return. The permanent
magnet brake has a torsionally stiff connection to the motor rotor. This is the reason that this
brake has no play.
NOTICE
Damage due to axial forces on the S120M with holding brake
On an S120M with integrated permanent-magnet-excited holding brake, axial forces at the
shaft extension can cause damage. This applies when installing the system and during
operation.
● Lock the components connected to the shaft in place.
5.11.2 Connection at the S120M
The motor holding brake is controlled, integrated in the S120M.
S120M
5.11 Motor holding brake
106
Manual, 06/2019, 6SL3097-5AW00-0BP1