Lenze DSD - Manual (Page 428)

17 Restrictions of the drive dimensioning
17.6 Mechanical brakes for winding drives
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Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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The limit frequency at the inverter input can be exceeded if the feedback system outputs a too high
pulse frequency due to the combination of number of increments and max. speed. A check in the
DSD does not take place.
• The compliance with these criteria must be checked manually.
17.6 Mechanical brakes for winding drives
Due to high moments of inertia and high material speeds, rotating reels may store high amounts of
kinetic energy which must be dissipated quickly in the event of an emergency stop. Only effective
and sufficiently dimensioned electrical, electromechanical brakes and sometimes also mechanical
brakes are able to dissipate these energies. A combination and coordination of multiple braking sys-
tems is possible.
• Winding drives must be equipped with at least one brake assembly, either as motor brake or in-
dependent separate brake, which is able to safely brake the drive with a defined frequency and
a defined braking distance in the event of an error.
• For very high moments of inertia and speeds, we recommend to additionally use e.g. disc brakes
to unload the drive during the braking phase. The additional brake can act as redundant system
at the same time.
• The brake control must be carried out on two channels.
• For a drive dimensioning with electromechanical motor brake, DSD calculates the brake as hold-
ing brake with a certain reserve. The reserve factor is indicated in the dimensioning protocol. In
addition, the motor brake must be dimensioned as service brake, under consideration of the
max. permissible friction energy of the brake.
Permanent magnet holding brake (PMB)
Permanent magnet holding brakes have a reduced braking torque at higher speeds (speed-depend-
ent torque drop). At zero speed, the torque may drop down from 100 % to 20 % of the characteristic
braking torque.
If the brake (service brake) features a safety-relevant function, you must not use a permanent mag-
net holding brake.
• In case of an emergency (electrical braking by the inverter fails), the drive is not braked safely.
• Additionally use a redundant brake assembly outside of the motor, or a motor with a spring-ap-
plied brake (BFK).
• A service brake must be dimensioned and checked manually. DSD only dimensions a motor
brake as holding brake, not as service brake.