Residual Risk - Siemens SINAMICS S120 Function Manual

System features

3.5 Residual risk

3.5 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:
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.
• Faults in the absolute track (C-D track), cyclic interchange of the drive phases (V-W-U
• Simultaneous failure of two power transistors (one in the upper and the other offset in
• Violation of limits may briefly lead to a speed higher than the speed setpoint, or the axis
• Mechanical forces greater than the maximum drive torque may force a drive currently
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WARNING
WARNING
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 60204-1:2006
(fault response functions STOP B to D in accordance with Safety Integrated) are not
activated.
Stop function category 0 to EN 60204-1:2006 (fault response function STOP A to Safety
Integrated)) is not triggered until after the transition or delay time set in the parameter
has elapsed. These faults are detected when SBR is selected (fault reaction functions
STOP B/C) and stop function category 0 to EN 60204-1:2006 (fault reaction 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.
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
Synchronous linear motors: max. movement = pole width
WARNING
may pass the defined position to a certain extent, depending on the dynamic response
of the drive and on parameter settings.
operated in position control mode out of Safe Operating Stop state (SOS) and trigger
stop function category 1 to EN 60204-1:2006 (fault reaction function STOP B).
Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
Safety Integrated