Siemens SINUMERIK 840D sl Function Manual page 102

Safety functions integrated in the system/drive
7.1 Safe standstill (SH)
Potentially hazardous motion
If the safe standstill function or "STOP A" is activated, then the motor can no longer generate
any torque. This is the reason that potentially hazardous motion can occur, e.g. for the
following:
● When an external force acts on the drive axes
● Vertical and inclined axes without weight equalization
● Axes that are moving (coasting down)
● Direct drives with low friction and low self-locking
● Cogging torques (depending on the motor type, bearing design and friction characteristics,
Possible hazards must be clearly identified using a risk analysis that must be carried out by
the manufacturer. With an assessment, based on this risk analysis, it should be defined as
to which additional measures are required, e.g. external brakes.
Functional features
The main features of the safe standstill function are as follows:
● The motor cannot be started unintentionally or accidentally
● The energy feed to the motor is safely disconnected
● The Motor Module and motor are not electrically isolated from one another
Selecting/deselecting SH
The safe standstill function corresponds to an external STOP A. This makes it possible to
explicitly select SH, not only using internal events (STOP A when a limit value is violated), but
also via SGE.
● Safe standstill is activated after a STOP A.
● Safe standstill is automatically activated from every monitoring channel when testing the
switch-off signal paths.
Note
When selecting/deselecting SH, motion monitoring functions such as SBH, SG, n<n
are not influenced. For instance, when manually turning a spindle in the SH state, with SBH
simultaneously selected, then this results in Alarm 27010. When required, users must take
this into account in the safe programmable logic (SPL).
102
WARNING
up to half a pole pitch in a direction that cannot be predicted)
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
, SE, SN
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Safety Integrated