SIEMENS
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Siemens D 11 · 2015
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Function
(continued)
2
Highlights
Safety Integrated
Safe Brake Test (SBT)
The SBT function carries out a brake function test at regular
intervals.
Activation
A good way to check the proper functioning of brakes that have
become worn is to apply a torque to the closed brake. Drive sys-
tems that have two brakes, e.g. motor brake and external brake,
can be tested with different torque values.
Application
The SBT function is suitable for implementing a safe brake in
combination with the SBC function.
Customer benefits
The function detects faults or wear in the brake mechanics. Au-
tomatically testing the effectiveness of brakes reduces mainte-
nance costs and increases the safety and availability of plants/
machines.
Safely-Limited Speed (SLS)
The SLS function ensures that the drive does not exceed a pre-
set speed limit.
Activation
The SLS function monitors the drive against a parameterized
speed limit. Four different limit values can be selected. As in the
case of SOS, the speed setpoint is not influenced independently.
After SLS has been selected, the higher-level control must bring
the drive down below the selected speed limit within a parame-
terizable time. If the speed limit is exceeded, a customizable
drive-integrated fault reaction occurs.
The SLS limit stage 1 can be multiplied by a factor that is trans-
ferred in 16-bit resolution via PROFIsafe. This allows an almost
unlimited number of limits to be specified.
Application
The SLS function is used if people are in the danger zone of a
machine and their safety can only be guaranteed by reduced
speed. Typical application cases include those in which an op-
erator must enter the danger zone of the machine for the pur-
poses of maintenance or setting up, such as a winder in which
the material is manually threaded by the operator. To prevent in-
jury to the operator, the roller may only spin at a safely reduced
speed. SLS is often also used as part of a two-stage safety con-
cept. While a person is in a less critical zone, the SLS function is
activated, and the drives are only stopped in a smaller area with
higher potential risk. SLS can be used not only for operator pro-
tection, but also for machinery protection, e.g. if a maximum
speed must not be exceeded.
Customer benefits
The SLS function can contribute to a significant reduction in
downtime, or greatly simplify or even accelerate setup. The over-
all effect achieved is a higher availability of the plant. Moreover,
external components such as speed monitors can be omitted.
G_D211_XX_00311
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SBT
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SLS
G_D211_XX_00307
© Siemens AG 2015