Siemens SINAMICS S110 - Safe Speed Monitor Without Encoder

Safety Integrated Functions
8.5 Safety Integrated Extended Functions
Function Manual
Function Manual, 01/2011, 6SL3097-4AB10-0BP3
385
8.5.7.2 Safe Speed Monitor without encoder
Function
Set p9306 = p9506 = 1 or p9306 = p9506 = 3 (factory setting = 0) to activate Safety
Integrated functions without encoder. You can also make this setting by selecting "Without
encoder" on the Safety screen in STARTER.
Without an encoder, the "Safe Speed Monitor" essentially functions exactly the same as
described in the previous section under "Safe Speed Monitor with encoder".
Differences between Safe Speed Monitor with and without encoder
● For Safe Speed Monitor without encoder, after pulse suppression the drive is unable to
determine the current speed. Two responses can be selected for this operating state with
parameters p9309.0/p9509.0:
– p9309.0 = p9509.0 = 1
The status signal (SSM feedback signal) displays "inactive" (factory setting).
– p9309.0/p9509.0 = 0
The status signal (SSM feedback signal) is frozen. "Safe Torque Off" (STO) is
selected internally.
● Due to the less precise speed identification, "Safe Speed Monitor without encoder"
requires a higher hysteresis (p9347/p9547) and, where applicable, a filter time
(p9345/p9545) compared with the function with encoder.
Sequence diagram
The diagram below shows the signal profile for the case p9309.0/p9509.0 = 0.
The speed remains below the limits of p9346/p9546 throughout the entire observation
period. This is the reason that the SSM feedback signal r9722.15 = 1. The motor speed
drops after the command to suppress pulses. The internal STO is set when the speed drops
below the zero speed detection level.
The SSM monitoring remains active. The motor speed continues to be below the speed limit
p9346/p9546. The SSM feedback signal remains as 1, i.e. it is frozen.
To restart the motor safely, the STO must be selected manually and deselected once more.
After the STO has been deselected, a 5 second time window is opened. If the pulse enable
takes place within this time window, the motor starts. If the pulse enable does not take place
within this 5 second time window, the internal STO becomes active once more.