In the example, the controlled stop can be achieved using the delayed outputs of A1.
The controlled stop is not an integrated security function in the drive. Therefore, its
circuit is not shown in the figure.
According to UNI EN ISO 13849-1:2016, the subsystem to the input and output devices can reach
PL=e because:
l
The channels are redundant
l
The switches SW1 and SW2 have high MTTFd and DC
l
The SW2 switch operates with positive opening
l
Q1 and Q2 have high MTTFd and DC
l
CCF value is > 65
Subsystems:
l PLC A1 has PL = e
l DM2020 drive (STO circuit) has PL = e
The security system can reach PL = e and the Category is 4.
According to CEI EN 62061: 2005 +A1:2013 +A2:2015, the subsystem to the input and output
devices can achieve SIL 3 because:
l
All safety-related devices have PFHd <10
-7
Subsystems:
l Safety PLC A1 has SIL 3
l DM2020 drive (STO circuit) has SIL 3
The safety system can reach SIL 3.
10.7.2 Example Requirements
l Before activating the STO function, it is necessary to stop the motor while maintaining the
power supply during the stop (controlled stop).
l Delay of outputs A1, which operate the contactors Q1 and Q2, should be > T (general shutdown
capability).
l The A1 safety PLC has to fulfill the requirements for PL e according to UNI EN ISO 13849-1:2016.
l The Q1 and Q2 safety contactors should be linked to contacts according to IEC 60947-5-2,
Annex L ("mirror contacts").
l In accordance with the risk assessment, when it is possible that personnel can physically enter
the danger zone, i.e., beyond the protective cover or barrier: either a detection system must be
installed; or, the restart must be available only after the safety guards are back in place and it
is confirmed that no personnel is in the danger zone.
l A short circuit between conductors connected to 33-34 A1, between conductors connected to
37-38 A1, and between those connected to pins 1 and 2 of the drive must be avoided.
l There must be physical separation between signal paths.
PN: L-MAM2-E-201
Moog Casella DM2020 Installation and Startup Guide
10.7.2 Example Requirements
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