SIEMENS
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Siemens D 31 · 2015
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Function
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
systems 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.
Automatically testing the effectiveness of brakes reduces main-
tenance 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
preset 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
operator 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 2014