ABB Triguard SC300E Safety Manual

Also see for Triguard SC300E: User manual

Contents

ABB Triguard SC300E Safety Manual Manual pdf 18 page image

Issue 5 - September 2006 Page 18 of 653.4.2 Without Time Constraint Dual OutputsIn AK6 (SIL 3) classified safety loops with only one final element, then the final element must becontrolled from two digital output channels on separate digital output modules. (Figure 4 showsa typical configuration).Figure 4 Dual outputs to single final element3.4.3 Interposing DevicesThe use of interposing devices such as IS barriers and relays are not part of the certified PLCsystem and must be considered for reliability as part of the field loop. However, the following isrecommended.IS barriers should be certified (Germany PTB / BASEEFA / SEV) and compatible with both theTriguard SC300E I/O module and the field device. Where barriers are mounted onmanufacturer’s barrier termination card, the PLC certification ends at the barrier termination cardsafe area connection.Simplex Interposing relays should be configured with 2-pole isolation in order to eliminatesimplex fail to danger modes.Where interposing relays operation is only to be monitored by contact feedback from the relaythese should be safety type relays.It is the responsibility of the system designer to advise the end user of all such devices that areincluded within the safety systems scope of supply in order for the end user to evaluate thereconfiguration and suitability for the complete safety loop.3.4.4 Systematic Software FaultsTo provide further tolerance to systematic design and application software faults, for examplecontinuous loops, the application TMR watchdog is incorporated. An example of its applicationis shown in the example networks.3.4.5 Process Fault Tolerant TimeThe configuration must ensure that the specified process fault tolerance time must be equal orgreater than twice the PLC cycle time plus the field equipment switching time. The PLC cycletime can be estimated from the scan rate data estimator (Triguard SC300E Scan Rate EstimatorSS 0730) and may be confirmed by monitoring the three registers available for displaying: -R1980 - Scan Rate Set in centisecondsR1981 - Scan Rate Time in centisecondsR1982 - Scan Rate Used in centisecondsFor full details refer to the TriBuild Help Facility.SingleSafetyValveDual Channel ControlMDO Card 1 TCMDO Card 2 TCSC300E TMRSystemRelay 1Relay 2Field PowerSupply