Safety Integrated Functions
8.3 System features
Function Manual
350 Function Manual, 01/2011, 6SL3097-4AB10-0BP3
8.3.6 Residual risk
The fault analysis enables the machine manufacturer to determine the residual risk at his
machine with regard to the drive unit. The following residual risks are known:
WARNING
Due to the intrinsic potential of hardware faults, electrical systems are subject to additional
residual risk, which can be expressed by means of the PFH value.
WARNING
Faults in the absolute track (C-D track), cyclic interchange of the drive phases (V-W-U
instead of U-V-W) and reversal of the control direction may cause acceleration of the
drive. Due to the fault, however, Category 1 and 2 stop functions to EN 60204-1 (fault
response functions STOP B to D in accordance with Safety Integrated) are not
activated.
Stop function Category 0 to EN 60204-1 (fault response function STOP A in accordance
with Safety Integrated) is not triggered until after the transition or delay time set in the
parameter has elapsed. These faults are detected when SAM is selected (fault response
functions STOP B/C) and stop function category 0 in accordance with EN 60204-1 (fault
response function STOP A in accordance with Safety Integrated) is triggered as early as
possible regardless of this delay. Electrical faults (defective components or similar) may
also lead to the response stated above.
Simultaneous failure of two power transistors (one in the upper and the other offset in
the lower inverter bridge) in the inverter may cause brief movement of the drive,
depending on the number of poles of the motor.
Maximum value of this movement:
Synchronous rotary motors: Max. movement = 180° / no. of pole pairs
WARNING
Violation of limits may briefly lead to a speed higher than the speed setpoint, or the axis
may pass the defined position to a certain extent, depending on the dynamic response
of the drive and on parameter settings.
Mechanical forces greater than the maximum drive torque may force a drive currently
operated in position control mode out of the Safe Operating Stop state (SOS) and
trigger stop function category 1 in accordance with EN 60204-1 (fault reaction function
STOP B).
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