Circuit with OSSD (SIL 3)
Fig. 97: Wiring with OSSD
Fig. 97: Wiring with OSSD
The following figure shows a circuit without OSSD safety device, whilst only safety di-
rected command devices with forcibly opened contacts in two-channel design are used.
SIL 3 (according to EN ISO 13849-1) is achieved. It is also possible to cascade sever-
al different safe emergency stop devices, position switches or door locks to one safety
circuit.
Circuit without OSSD (SIL 3)
Fig. 98: Wiring without OSSD
Fig. 98: Wiring without OSSD
Note
The safety switch device as well as the emergency stop device have to be certificated
as safety devices of at least level SIL 3 to obtain safety level SIL 3 according to EN ISO
13849-1.
Note
In order to obtain the safety level SIL 3 according to EN ISO 13849-1 the circuit and the
layout have been dimensioned according to IEC 60664-1:2008-01. Supporting materi-
al according to IEC 60249 covered by a nonaging protective coat of lacquer according
to IEC 60664-3:2003-09 have been used. The conformity of standard have been tested
and approved by the TÜV-Nord CERT.
19.3 Requirements and Standards
The following parameters are achieved according to the safety case:
▸
according to EN ISO 13849-1:2008-12
– MTTFd: >100 years
– DC = 99%
– Category 4
179Drive System SD2 - Hardware Description
Safety circuit / restart lock (STO)
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