Encoderless Safely Limited Speed - Siemens SINAMICS S120 Function Manual

5.6.2

Encoderless Safely Limited Speed

If an induction motor is being used, Safely Limited Speed (SLS) can also be activated
without an encoder.
Features
After SLS has been triggered, measures should be taken to ensure the motor is immediately
decelerated with the OFF3 ramp from the current speed to below the selected SLS [1...4]
speed limit. Monitoring is activated after delay time p9582/p9382 (SI Motion brake ramp
delay time Control Unit/Motor Module) has elapsed. Monitoring ensures the motor does not
exceed the set brake ramp (SBR) during braking.
The new SLS speed limit is accepted as the new limit speed if either the brake ramp has
reached the new SLS speed limit or the actual speed of the drive was below the new SLS
speed limit for at least as long as p9582 (SI Motion brake ramp delay time Control Unit).
The SLS function then monitors whether the new actual speed remains below the selected
SLS speed limit. The programmed STOP response is triggered as soon as the limit speed is
exceeded.
Configuring the limits
Speed limits for encoderless SLS are configured in exactly the same way as described for
SLS with an encoder.
Differences between SLS with and without an encoder
The SLS with encoder function monitors whether the motor remains under the set limit
speed. During deceleration to a lower limit speed, SBR also monitors whether the drive has
dropped below the lower limit speed within the delay time specified. If this is not the case,
messages C01714 and C30714 are output.
The SLS without encoder function monitors whether the motor remains under the set limit
speed during operation. During deceleration to a lower limit speed, SLS acts as a monitor to
ensure the motor does not exceed the set brake ramp. If the brake ramp is violated,
messages C01707 and C30707 are output and the drive is stopped with STOP A or STOP B
(depending on the setting made).
Safety Integrated
Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
Safety Integrated Extended Functions
5.6 Safely-Limited Speed (SLS)
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