SIEMENS
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Siemens CR 1 · 2015
7
SIMOTICS motors for cranes
SIMOTICS SD – Severe Duty motors
KFB spring-set brake for SIMOTICS SD 1LP4, 1LP6
■
Configuration
The following dimensioning parameters must be taken into
account when a brake is selected:
Braking torque
On the assumption that the deceleration rate must be approxi-
mately equal to the acceleration rate, the braking torque should
be calculated as follows:
M
BR
=
M
Ja
×
η
2
Accordingly, the braking torque of the mechanical brake must
be approximately equal to the required maximum motor torque.
Braking energy on emergency trip
The braking energy for occasional emergency trips must be
checked to ensure that it does not cause the brake to overheat.
Please refer to table in section "Technical specifications" for per-
missible values. The braking energy produced for traversing
gear can be calculated approximately with the following equa-
tion:
The total moment of inertia
I
tot
is the sum of the individual mo-
ments of inertia of the plant components to be braked, reduced
to the brake (motor) shaft, and the moment of inertia of the linear-
motion masses. The equivalent mass inertia
I
Eqv
of a linear-mo-
tion mass
m
with velocity
v
, referred to the brake (motor) speed
n
Br
, is calculated as follows:
The velocity and/or speed to be entered here must equal the ma-
ximum values in normal operation. An increase in velocity resul-
ting from wind forces may also need to be taken into account.
M
BR
Braking torque of the mechanical brake
M
Ja
Accelerating torque for accelerating linear-motion and rotating mas-
ses
Q
Energy capability/braking energy in kJ
M
Br
Existing braking torque in Nm
M
L
Total of all load torques in Nm referred to the brake (motor) shaft
n
Br
Speed of brake (motor) shaft in rpm
I
tot
Total moment of inertia to be braked in kgm
2
reduced to the brake
(motor) shaft
M
L
is positive if it supports braking (e.g. hoisting a load)
M
L
is negative if it counteracts braking (e.g. lowering a load)
m
Mass of the linear-motion load in kg
ν
Velocity of the linear-motion load in m/s
n
Br
Speed of brake (motor) shaft in rpm
Q =
[
kJ
]
I
tot
×
n
2
Br
182.4
×
10
3
×
M
Br
M
Br
±
M
L
I
Ers
=
91.2 ×
m ×
(
)
2
[
kgm
2
]
n
Br
v
© Siemens AG 2015