Motor components
5.3 Holding brake (option)
1FT7 Synchronous Motors
208 Configuration Manual, (PFT7S) 01/2009, 6SN1197-0AD13-0BP2
5.3 Holding brake (option)
5.3.1 Properties
● The holding brake is used to clamp the motor shaft when the motor is at a standstill. The
holding brake 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 300% 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.
● The rated voltage of the holding brake is 24 VDC.
CAUTION
The rated voltage is 24 VDC +/- 10%. Voltages outside this tolerance bandwidth can
result in faults.
Inadmissible wear means that the braking function can no longer be guaranteed! It is not
permissible to exceed the above specified Emergency Stop conditions or to repeatedly
briefly accelerate the motor against a holding brake that is still closed. This means that
the switching times of the brakes and relays must be taken into account in the drive
control and enable functions.
NOTICE
Motors with or without holding brake cannot be subsequently retrofitted!
Motors with holding brake are longer by the mounted space required (refer to the
dimension drawings).
5.3.2 How it works
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 24 V DC 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 torsion-proof connection to the rotor of the motor. This is the
reason that this brake is almost without any play.
CAUTION
Motors with integrated permanent-magnet holding brake cannot be subject to axial forces at
the shaft end! This applies when installing the system and during operation.
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