Slide background




Il nuovo Standard ISO 24119 e il massimo PL raggiungibile in caso di serie di dispositivi di interblocco

ID 1610 | | Visite: 12184 | Documenti Estratti NormePermalink: https://www.certifico.com/id/1610




ISO/DTR 24119
Safety of machinery - Evaluation of fault masking serial connection of guard interlocking devices with potential free contacts.

This is currently under committee review, with an expectation that it will be available quite soon as ISO/TR 24119.

This TR has not been published but it will deal with.

The Technical Report illustrates and explains principles of fault masking in applications where multiple interlocking devices with potential free contacts are connected in series to one logic unit which does the diagnostics.

It provides also a guide how to estimate the probability of fault masking and the maximum DC for the involved position switches.

In simple terms, if we have more than one frequently opened guard (once per hour) the level of Diagnostic Coverage falls to zero, which in EN ISO 13849-1 results in a maximum PLc.

It remains to be seen exactly what ISO/PDTR 24119 has to say about the maximum PL achievable when several infrequently operated guards are connected, but it is very likely to be PLd where careful analysis is possible (for example, the number of guards, the type of switches, type of wiring, distance between guards, and accessibility of guards), otherwise it is more likely to be PLc.

It is definitely not possible to achieve PL e with more than one guard switch connected in series, at least not when using volt-free based interlock switch technology.

Early signs are that the technical report ISO/PDTR 24119 will provide two methods for evaluating the extent to which diagnostic coverage is impacted by masking:

1. Simplified method for the determination of the maximum achievable DC

Table 1 provides a simplified approach for the determination of the maximum achievable DC taking into account the probability of masking.

If the maximum achievable DC resulting from the application of this table does not meet the required level, the more detailed approach given in 2 may be more suitable - but this is not ideal.


2. Regular method for the determination of the maximum achievable DC

2.1 Estimation of the fault masking probability

The probability of fault masking is dependent on several parameters that should be considered, including:

  • Number of series connected devices
  • Actuation frequency of each movable guard
  • Distance between the movable guards
  • Accessibility of the movable guards
  • Number of operators

The maximum achievable DC depends on the fault masking probability level (FM) and the type of cabling used in combination with the switch arrangement and the diagnostic capabilities of the overall system to detect faults.

Tables 3 to 5 show the maximum reachable DC depending on those parameters.

In any case, if it is foreseeable that fault masking will occur (eg multiple movable guards will be open at the same time as part of normal operation or service), then the DC is limited to none.

It is beyond the scope of this article to go into the details of tables 3 and 5 referred to above, and it is recommended that, instead, the 'simplified method outlined in 2 above is used.
...
in allegato Preview

Descrizione Livello Dimensione Downloads
Allegato riservato ISO TR 24119 2015 Preview.pdf
 
270 kB 8

Tags: Normazione EN ISO 14119 Abbonati Normazione

Articoli correlati

Ultimi archiviati Normazione

Set 22, 2023 31

UNI 11911:2023

UNI 11911:2023 / Qualificazione stabilimenti balneari ID 20451 | 22.09.2023 UNI 11911:2023Stabilimenti balneari - Requisiti e raccomandazioni per l'esercizio dell'attività - Elementi di qualificazione Data disponibilità: 21 settembre 2023 _______ La norma fornisce agli operatori del settore… Leggi tutto
Decisione di esecuzione  UE  2023 1759
Set 12, 2023 745

Decisione di esecuzione (UE) 2023/1759

Decisione di esecuzione (UE) 2023/1759 / Norme armonizzate per le lavastoviglie per uso domestico 09.2023 ID 20381 | 12.09.2023 Decisione di esecuzione (UE) 2023/1759 della Commissione dell'11 settembre 2023 relativa alle norme armonizzate per le lavastoviglie per uso domestico elaborate a sostegno… Leggi tutto
Set 11, 2023 751

UNI 11764:2019

UNI 11764:2019 / Requisiti di prova piccoli trabattelli ID 20376 | 11.09.2023 / In allegato Preview Piccoli trabattelli su due ruote - Requisiti e metodi di prova La norma specifica i requisiti e i metodi di prova dei piccoli trabattelli su due ruote con l'altezza del piano di lavoro minore di 4 m… Leggi tutto
ISO 8025 2023
Ago 30, 2023 266

ISO 8025

ISO 8025 / Management of working conditions in hot environments ID 20272 | 30.08.2023 / Status: FDIS - Edition: 1 ISO 8025:2023Ergonomics of the thermal environment : Management of working conditions in hot environments Final text received or FDIS registered for formal approval Aug 2, 2023 Scope of… Leggi tutto

Più letti Normazione