Functional safety
FUNCTIONAL SAFETY
Design Requirements
9.
QC-PDS
HARDWARE
Ref.2003
· 309 ·
9.4 Design Requirements
This section describes some of the design requirements for the use of the
QC-DR drive.To obtain information about the wiring, see 9.9 CABLING AND
GROUNDING.
Power-up
On power-up, the external safety controller must demand the safety
function.
The safety controller
Drive safety functions extend to Cat. 3, PL d - SIL 2. When a machine
safety functions requires PL d or SIL 2, it requires an external safety
controller PL d or SIL 2 that provides two different channels to demand
the safety functions. See 9.3 FAULT DETECTION AND REACTION.
Safe Stop 1 ·SS1·
EXAMPLE 2 shows an implementation of a “safe stop 1 time controlled SS1-
t” SS1 according to IEC 61800-5-2. This is a category 1 stop as stated in
IEC 60204-1.
It starts the motor deceleration and performs the STO function after a delay
time t that has been previously specified for the application, but it does not
monitor that the breaking is performed successfully, and thus the SS1-t has
a residual risk. See SS1-T in 9.6 RESIDUAL RISKS.
In order to perform the SS1, the safety controller will activate and Input in
the FAGOR PLC that will activate SPENA and in this way, all the motors
will be stopped by the CNC.
Depending on whether the door is closed or not, the tool could be retract or
even move it to a safe position.
Once the configured time limit in the safety controller expires, the safety
controller will demand the STO and if the machine has a holding brake in
the vertical axis, it will close it ·see SAFE BRAKE CONTROL (SBC)·. In order to
avoid a slight vertical movement in the vertical axis, the FAGOR PLC (no
SRP/CS) would already have closed the holding brake previously.
See also, RESPONSE TIME OF THE HOLDING BRAKE.
PFH calculation for the safe stops of the machine
In order to stop the machine safely, the safety controller must request to
each drive to stop its motor (or its two motors in case of dual-drive). This
stop can be made with SS1 or STO, keep in mind that SS1 does demand
STO at the end.
In this way, the PFH of any of the two types of emergency safety stops,
using SS1 or STO, will be the same, and equals the following sum:
PFH emergency stop button
+ PFH safety controller
+ sum of the PFH of all the STO involved
INPUT
Sub-System
X13A
(dual-drive)
QC-DR
Emergency
Button
LOGIC
Sub-System
External Safety
Controller
Safe T orque Off
ACTUATOR
Sub-System
channel 2
STO 1
channel 1
X13B
STO
feedback
STO 2
STO 1
STO 2
Emergency stop sub-system from
EXAMPLE 2
To Next Page
Loading...