Lenze MDFQA Operating Instructions - Manual (Page 23)

Mechanical installation
Holding brake (option)
Installation
5
EN
23 Lenze ¯ BA 33.0006 ¯ 3.0
The brakes operate according to the closed−circuit principle, i.e. the brake is closed in the
deenergised state. The brakes for DC supply can be fed with a bridge−rectified DC
voltage (bridge rectifier) or with a smoothed DC voltage. Information on the permissible
voltage tolerance is provided in the respective motor catalogue.
If long motor supply cables are used, pay attention to the ohmic voltage drop along the
cable and compensate for it with a higher voltage at the input end of the cable.
The following applies to Lenze system cables:
U *
+ U
B
)
ƪ
0.08 W
m
@ L @ I
B
ƫ
U* [V] Resulting supply voltage
U
B
[V] Rated voltage of the brake
l [m] Cable length
I
B
[A] Rated current of the brake
(
Stop!
If no suitable voltage (incorrect value, incorrect polarity) is applied to the
brake, the brake will be applied and can be overheated and destroyed by
the motor continuing to rotate.
The shortest operating times of the brakes are achieved by DC switching of the voltage
and a suppressor circuit (varistor or spark suppressor). Without suppressor circuit, the
operating times may increase. A varistor/spark suppressor limits the breaking voltage
peaks. It must be ensured that the power limit of the suppressor circuit is not exceeded.
This limit depends on the brake current, brake voltage, disengagement time and the
switching operations per time unit.
Furthermore, the suppressor circuit is necessary for interference suppression and also
increases the service life of the relay contacts (external, not integrated in the motor).
,
Please refer to the catalogue for servo motors for detailed information
about holding brakes.
)
Note!
The brake cannot be readjusted. When the wear limit is reached, the
brake has to be replaced.