Siemens SINUMERIK Series Function Manual page 35

Example of how the function can be used
● Controlled braking of a drive in SOS.
How does SS2 function in detail?
Overview
The safety function SS2 monitors the load speed and initiates the SOS function if the SS2
delay time has expired.
With SS2, braking is monitored along the OFF3 ramp. Incorrect acceleration is identified and
the drive then shuts down with STO.
If you are operating the motor with closed-loop torque control, the inverter switches to the
closed-loop speed control mode when SS2 is selected.
Detailed description
The SS2 safety function operates as follows:
● The machine control selects the SS2 safety function using a fail-safe input:
– If the motor is already at a standstill when selecting SS2, after a delay time, the inverter
– If the motor is not at standstill when SS2 is selected, it is braked along the OFF3 ramp.
● After a delay time, the inverter activates the Safe Operating Stop function (SOS). This
function safety monitors the standstill of the drive.
Safety Integrated
Function Manual, 10/2015, 6FC5397-3EP40-5BA3
activates the Safe Operating Stop function (SOS).
Braking is monitored using the Safe Acceleration Monitor (SAM) function. Incorrect
acceleration is therefore detected.
Overview of Safety Integrated functions
2.3 Safety Integrated Extended Functions
35