ABB AC500-S Application Note

Also see for AC500-S: System manual Safety user manual Safety user manual Operation manual

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ABB AC500-S Application Note Manual pdf 18 page image

Application Note for “Usage of AC500 digital standard I/Os in functional safety applications up to PL c (ISO 13849-1)”, V1.0.0Page 18/24We reserve all rights in this document. Reproduction, use or disclosure to third parties without express authority is strictly forbidden. Ó 2015 ABB Ltd.NOTICEThe data transfer (C0 channel state) from DC523 to PM573 andthen further to SM560-S Safety CPU introduces some time jitter.The largest introduced time jitter is usually caused bySF_DPRAM_PM5XX_S_REC and SF_DPRAM_PM5XX_S_SENDFBs. This leads to longer supervised time values (e.g., LOW phaseof 35 ms and HIGH phase of 400 ms can be used as limits) thanthose specified in Figure 5. These limit values can, however, varydepending on selected settings for tasks on PM573, SM560-S, “MinUpdate Time” parameter for SM560-S and selected data transfermethod between PM573 and SM560-S.NOTICEDue to the introduced jitter in the used test signal pattern, as onecould see from Step 4, the effective input delay used for C0 inputchannel becomes 35 ms (DiscrepancyTime := T#35ms, see Step 4above). The longest tolerated HIGH phase (+24 V) before “Stuck-At-1” error is detected and then safe reaction is triggered (to be im-plemented as part of the safety application program) becomes (Dis-crepancyTime := T#400ms, see Step 4 above). These values shallbe further used in SFRT and fault reaction time calculations.NOTICEThe test rate (the test period of 450 ms was used in the given ex-ample) for input part of the safety function shall be at least 100 timesgreater than the demand rate upon the safety function, as requiredfor Category 2 (ISO 13849-1).This requirement is fulfilled in the given example for PL c safetyfunction if the demand is less than 1 per 45 seconds.3.4.2 Common cause failuresAll measures for CCF are already covered for AC500-S Safety PLC modules likeSM560-S and DX581-S, which are certified for up to PL e (ISO 13849-1) and SIL CL 3(IEC 62061) safety applications. However, for all AC500 standard (non-safety) mod-ules, like PM573 and DC523, the estimation of CCF effect shall be performed usingAnnex F, ISO 13849-1.We use below the scoring process and quantification of measures against CCF basedon Annex F, ISO 13849-1:1. Physical separation between signal paths, refer to AC500 design process(see Chapter 3.4.3) – 15 points- Sufficient clearances and creepage distances on printed-circuit boards2. Design/application/experience (Protection against overvoltage), refer toAC500 design process (see Chapter 3.4.3) – 15 points3. Environmental (EMC, etc.), refer to CE declaration type test report for agiven AC500 product – 25 points