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DOK-MOTOR*-MSK*EXGIIK3-PR09-EN-P
Synchronous Servomotors MSK For Potentially Explosive Areas
Checking the holding brake during
operation (recommendation)
10.10.3
Design of holding brakes
Dynamic design
●
Information Sheet No. 005 "Gravity loaded axes (vertical axes)" - pub‐
lished by: Technical Committee Mechanical Engineering, Manufacturing
Systems, Steel Construction
For the US:
●
See National Electrical Code (NEC), National Electrical Equipment Man‐
ufacturers Association (NEMA) and regional building codes.
The national regulations must be observed!
The permanent magnetic brake is no safety brake. This means, a torque re‐
duction by non-influenceable disturbance factors can occur (see EN 954; ISO
13849-1; ISO 13849-2 or Information Sheet No. 005 "Gravity loaded axes
(vertical axes)").
Particular attention must be paid to this:
●
Corrosion on the friction surfaces as well as vapors, exhalations and de‐
posits reduce the braking effect.
●
Lubricants must not get onto the friction surface.
●
Over-voltages and excessively high temperatures can permanently
weaken the permanent magnets and thus render the holding brake un‐
usable.
If the air gap between armature and pole increases due to wear, the function
of the holding brake is no longer guaranteed.
Faults which occur during the operating period and which may change the
design parameters or the operating conditions must be detected and elimina‐
ted within a reasonable period of time. In this case, we recommend checking
the function and condition of the holding brake at regular intervals.
Holding brakes on motors are generally not designed for service braking. The
effective braking torques are physically different in static operation and dy‐
namic operation.
Normal operation and EMERGENCY
STOP
In normal operation, using the holding
brake for clamping an axis in standstill,
the "static holding torque" (M4) – static
friction takes effect.
At an EMERGENCY STOP for stopping
an axis (n < 10 min
-1
), a "dynamic brak‐
ing torque" (M
) - sliding friction - takes
dyn
effect.
Therefore, please note the following description of the dynamic design.
Tab. 10-8:
Dynamic design
The load torque must be lower than the minimum dynamic torque M
the holding brake can provide. Otherwise the deceleration effect of the hold‐
ing brake is not sufficient to stop the axis.
In order to decelerate a mass in a defined time or over a defined distance,
the mass inertia of the whole system must be additionally taken into account.
Bosch Rexroth AG
Operating conditions and application notes
Malfunction
In the event of a malfunction, using the
holding brake to stop an axis in motion (n
≥ 10 min
) , a "dynamic braking torque"
-1
(M
) - sliding friction - takes effect.
dyn
M4 > M
dyn
133/175
which
dyn
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