Residual Risk - Siemens SINUMERIK Series Function Manual

Safety instructions

1.4 Residual risk

1.4 Residual risk
The fault analysis enables machine manufacturers to determine the residual risk at their
machine with regard to the drive unit. The following residual risks are known:
Danger to life as a result of hardware faults relating to the intrinsic principle: PFH value
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.
● Take into account these residual risks when designing your machine and where necessary
Danger to life when a drive accelerates in an uncontrolled fashion
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. Category
1 and 2 stop functions according to EN 60204-1 (fault response functions Stop B to D
according to Safety Integrated) that are provided are however not effective due to the fault.
● Category 0 stop function according to EN 60204-1 (fault response function Stop A
Danger to life when a drive moves when two power transistors simultaneously fail (breakdown
of depletion layer)
The simultaneous breakdown of depletion layer of 2 power transistors (one in the upper and
the other offset in the lower inverter bridge) in the inverter may cause the drive to move briefly.
This can result in accidents leading to death or severe injury.
● Take suitable measures to prevent unexpected drive movement, for example, by using a
Danger to life as a result of brief, higher speeds when limit values are violated
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. When accidents occur, this can result in death or severe injury.
● Take into account this situation when designing your machine and where necessary apply
20
WARNING
apply suitable countermeasures.
WARNING
according to Safety Integrated) is not activated until the transition or delay time set in the
parameter has expired. These faults are detected when SAM is selected (fault reaction
functions STOP B/C) and stop function category 0 according to EN 60204-1 (fault reaction
function STOP A according to 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.
WARNING
brake equipped with safety monitoring (Safe Brake Control).
WARNING
suitable countermeasures.
Function Manual, 10/2015, 6FC5397-3EP40-5BA3
Safety Integrated