Slide background




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

ID 1610 | | Visite: 13224 | 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 13

Tags: Normazione EN ISO 14119 Abbonati Normazione

Articoli correlati

Ultimi archiviati Normazione

Mag 13, 2024 86

UNI 11900:2023

UNI 11900:2023 / Requisiti Installatore di sistemi di ancoraggio ID 21848 | 13.05.2024 / Preview in allegato Attività professionali non regolamentate - Installatore di sistemi di ancoraggio - Requisiti di conoscenza, abilità, autonomia e responsabilità La norma definisce i requisiti relativi… Leggi tutto
Mag 02, 2024 140

UNI EN ISO 3834-2:2021

UNI EN ISO 3834-2:2021 ID 21794 | 02.05.2024 UNI EN ISO 3834-2:2021Requisiti di qualità per la saldatura per fusione dei materiali metallici - Parte 2: Requisiti di qualità estesi La norma definisce i requisiti di qualità estesi per la saldatura per fusione dei materiali metallici sia in officina… Leggi tutto
Mag 02, 2024 127

UNI EN ISO 3834-1:2021

UNI EN ISO 3834-1:2021 ID 21793 | 02.05.2024 UNI EN ISO 3834-1:2021Requisiti di qualità per la saldatura per fusione dei materiali metallici - Parte 1: Criteri per la scelta del livello appropriato dei requisiti di qualità La norma fornisce uno schema generale della UNI EN ISO 3834 e i criteri da… Leggi tutto
Apr 28, 2024 153

UNI ISO 9926-1

UNI ISO 9926-1:1992 ID 21778 | 28.04.2024 / In allegato Preview UNI ISO 9926-1:1992 Apparecchi di sollevamento. Addestramento degli operatori. Generalità. Versione in lingua italiana della ISO 9926/1 (dic. 1990), adottata senza varianti. Specifica il minimo addestramento che deve essere dato ai… Leggi tutto
Norme armonizzate Direttiva imbarcazioni diporto 12 2017
Apr 25, 2024 191

Decisione di esecuzione (UE) 2024/1197

Decisione di esecuzione (UE) 2024/1197 / Norme armonizzate imb. da diporto Aprile 2024 ID 21757 | 25.04.2024 Decisione di esecuzione (UE) 2024/1197 della Commissione, del 23 aprile 2024, che modifica la decisione di esecuzione (UE) 2022/1954 per quanto riguarda le norme armonizzate per i sistemi… Leggi tutto

Più letti Normazione