Functional safety
FUNCTIONAL SAFETY
Main Characteristics of the Safety Functions
9.
QC-PDS
HARDWARE
Ref.2003
· 305 ·
9.1 Main Characteristics of the Safety Functions
These drives have the following safety functions:
Safe Torque Off
Definition
. Safe torque off. STO safety inputs that remove the motor
torque on the axis in a safe manner. STO correspond to an uncontrolled
stop according to stop category 0 of standard IEC 60204-1.
Availability. Always available.
and it is:
A type. Defined according to Section 7.4.4.1.2 of IEC 61508-2. See
also its appendix D.2.2.
Cat. 3 PL d - SIL 2
The safety functions extend to:
EN ISO 13849-1 Cat. 3 PL d
IEC 61508 SIL 2
See the requirements for THE SAFETY CONTROLLER in 9.4 DESIGN
REQUIREMENTS.
Channels of the safety functions
STO has a 1oo2 architecture - Cat. 3, with a dual channel with feedback.
Safe Torque Off (STO)
Input of the first channel
. Pins 1 and 2 of X13A and X13B (only in dual-
drive) connectors of the drive. Remove the torque for the axis.
Input of the second channel. Pins 3 and 4 of the X13A and X13B (only
in dual-drive) connectors of the drive. Remove the torque for the axis.
Common feedback to both channels
. The internal contacts (normally
closed) must be monitored through of pins 5 and 6 of the X13A and
X13B (only in dual-drive) connectors.
Safe state
The safety state of the drive is without motor torque.
The external safety controller may use the "Torque Off" state of the drive
to achieve a safe state of the machine
. In addition, if a holding brake is
necessary ·see UNCOMPENSATED FORCES ON A VERTICAL AXIS· the
controller must also close it so that the machine can reach the safe state.
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