Safe Operating Stop (Sos) - Bosch rexroth ctrlX SAFETY SafeMotion Applications Manual

Notes on project planning
When configuring the safety function "Safe Torque Off", it is absolutely neces-
sary to comply with the following safety instructions:
8.3.2

Safe operating stop (SOS)

Safety function description
If the safety function Safe operating stop (SOS) is active, the drive is in
controlled standstill, i.e. all control functions between the electronic control
unit and the drive are maintained. The dual-channel monitoring of the actual
position or the travel distance prevents the drive from carrying out dangerous
movements due to errors although the energy supply is not interrupted.
When the safety function "Safe operating stop (SOS)" has been selected, the
control unit can reset drive enable and set it again. The monitoring of the
standstill position always remains active.
R911404905, Edition 02
Safety functions in special mode "Safe standstill"
High electrical voltage! Danger to life, risk of injury by
WARNING
electric shock or serious personal injury!
During the time a safety function is active, power is not
removed from the motor; de-energize the drive before
working on the motor.
Lethal injury and/or property damage caused by unin-
WARNING
tended axis motion!
⇒ If external force influences are to be expected with
the safety function "Safe torque off", e.g. in the case of
a vertical axis, this motion has to be safely prevented by
additional measures, e.g. a mechanical brake or a coun-
terweight. For such axes, Bosch Rexroth recommends
using the Safe braking and holding system.
Injury and/or property damage caused by deviation from
WARNING
standstill position!
⇒ Even if power section control has been safely locked,
momentary axis motion, depending on the number of
poles of the motor, can be triggered, when two errors
are occurring simultaneously in the power section with
the voltage DC bus being active:
−
breakdown of a power semiconductor and
−
breakdown of another semiconductor
In this case, two of six semiconductors are affected in
such a way that the motor shaft is aligning.
Synchronous motor, for example: In the case of a syn-
chronous motor with 6 pole pairs, the motion can be a
maximum of 30 degrees. For a directly driven ball screw,
e.g. 20 mm per revolution, this corresponds to a one-
time maximum linear motion of 1.67 mm.
When an asynchronous motor is used, the short circuits
in two separate circuits of the power section have almost
no effect, because the exciter field breaks down when
the inverter is shut down and has completely died down
after approx. 1 s.
Lethal injury and/or property damage caused by unin-
DANGER
tended axis motion!
⇒ Please comply with the safety instructions in section
"Notes on project planning".
ctrlX SAFETY "SafeMotion"
Bosch Rexroth AG
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