SIEMENS
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Siemens MD 50.8 · 2017
Configuring guide
Configuring a brake
2
■
Brake switching time
The total time it takes the motor to come to a standstill comprises
the following times:
•
Brake application time
t
1
•
Braking time
t
br
The first is the time it takes the brake to reach 90 % of its braking
torque. This time may be circuit- and control-dependent.
The braking time is determined as follows:
If
T
x
supports the braking operation,
T
x
is positive; otherwise it is
negative.
■
Braking distance and positioning accuracy
Braking distance
s
br
is the distance traveled by the driven
machine during braking time
t
br
and application time
t
1
.
With linear motion, a positioning accuracy of between ± 12 %
and ± 15 % can be assumed. However, this can be heavily
influenced by the condition of the brake.
The formula below applies to horizontal motion and upward
vertical motion.
■
Cyclic duration factor
The cyclic duration factor
DC
of the brake (referred to a cycle of
max. 10 minutes) is the ratio between the ON period and the
duration of the duty cycle. The duty cycle is the sum of the
ON period and the no-voltage periods.
Fig. 2/10
Cyclic duration factor
Code
Description
Unit
DC
Cyclic duration factor
%
t
s
Close time (on-load factor)
s
t
O
Open time (off-load factor)
s
t
z
Cycle time (duty cycle time)
s
9.55 · (
T
br
±
T
x
·
)
t
br
=
(
J
G
+
J
AD
+
J
mot
+
J
z
+
J
x
·
) ·
n
br
s
br
v
t
1
1000
------------
0.5
t
br
+
=
D
C
t
s
t
s
t
O
+
----------------
100
=
t
s
t
O
t
z
Load
Time
G_D087_EN_00302
© Siemens AG 2017