Functional safety
FUNCTIONAL SAFETY
Main characteristics of the safety functions
9.
Ref.1912
· 313 ·
DDS
HARDWARE
9.1 Main characteristics of the safety functions
These drives have the following safety functions:
Safe Torque Off (STO)
Definition
. Safe torque off. Drive Enable safety input that works together
with the - KM1 contactor to eliminate the motor torque safely. STO
correspond to an uncontrolled stop according to stop category 0 of
standard IEC 60204-1.
Availability
. Always available.
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 - Cat. 3 architecture, with a double channel with feedback.
Safe Torque Off (STO)
- KM1 external contactor channel
. Eliminates the power to the power
supply input (PS, XPS or RPS)..
- KM1 contactor feedback
. To monitor, the contactor must have an N.C.
(
Normally Closed) contact and comply with standard IEC 60947-4-1 or
IEC 60947-5-1. See
note 3 of section 9.7 Technical data of the safety
functions
.
Drive Enable integrated channel input
. Pin 2 "Drive Enable" of the X2
connector of the AXD/SPD drive. Eliminates the motor torque.
AS1-AS2: Drive Enable feedback
. The N.C. contact (Normally Closed)
may be monitored through pins AS1-AS2 of connector X7.
Safe state
The safe state of the AXD/SPD drive is without motor torque.
The safe state of the machine. 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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