Programmable-controller safety

Thomas, Harold W. "A Quantitative Approach To The Use of Programmable Controllers in Safety Circuits". AIChE Loss Prevention Symposium Mar 1988. 

International Electrotechnical Commission. International standard lEC 61508 functional safety of electrical/electronic/programmable electronic safety related systems. Geneva 2000. Health and Safety Executive. Controlling the risks in the workplace. [Online]. 2015 [cited 2015 July. Available from http //www.hse.gov.uk/risk/controlling-risks.htm. 

This appendix presents a reliability and safety analysis of a number of programmable controller architectures. The architectures chosen represent a majority of those implemented. The architectures are listed in Table F-1. 

International Electrotechnical Commission [lEC] (1 ) 2005b. lEC 62061, Safety of machinery - Functional safety-related electrical, electronic and programmable electronic control systems. Geneva lEC International Electrotechnical Commission [lEC] (1 ) 2006. lEC 60770-3, Transmitters for use in industrial-process control systems Part 3. Geneva lEC International Electrotechnical Commission [lEC] (2 ) 2009. lEC 61508, Functional safety of electrical / electronic / programmable electronic safety-related systems — All parts. Geneva lEC... 

Brown S (2000). Overview of IEC61508- design of electric/electronic/ programmable electronic safety related systems. Confuting and Control Engineering Journal, February 2000. 

NOTE Instrumented systems in the process sector are typically composed of sensors (for example, pressure, flow, temperature transmitters), logic solvers or control systems (for example, programmable controllers, distributed control systems), and final elements (for example, control valves). In special cases, instrumented systems can be safety instrumented systems (see 3.2.72). 

Within the workplace, operational management at all levels has a responsibility to identify, evaluate and control risks that are likely to result in injury, damage or loss. Part of these responsibilities should involve implementation of a regular programme of safety inspections of the work areas under their control. These inspections should include physical examinations of the workplace - i.e. the nuts and bolts - and also the systems, procedures, and work methods - i.e. the organisational aspects. 

H. Bezecny, D. Inverso, V. Maggioli, G. Rabe, A. Weinert (Eds.), Guidelines for the Use of Programmable Controllers in Safety- Related Systems, vol. 13, October 1997. White paper 6009. 

One of the most important software safety standards is the International Electrotechnical Commission lEC 61508, Functional Safety of Electrical/ Electronic/Programmable Electronic Safety-Related Systems. It applies to all industries that use safety-critical systems that are electronically or software controlled. It uses safety processes described in Chapter 4 and in other safety analysis... 

Other programmable controllers used in machinery safety-related systems. In recognition of this, CEN is in the process of trying to map the principles of the standard into a new machinery sector version of lEC 61508, currently identified as prEN 62016. It is yet to be seen how this new standard, when it is eventually published, will relate to EN 954-1. 

As has previously been alluded to, there are two technological trends that will have a significant impact in the design of safety-related systems in the machinery safety sector. These are the introduction of PLCs for use in safety applications, so-called safety PLCs, and the development of safety field-buses. The availability of these systems will allow machinery designers to make full use of the advantages that programmable controllers and data communication networks have over the traditional hardwired safety solutions. 

In this chapter, the topic will be examined in the context of both electrical safety and the safety of electrotechnical control systems employing electrical, electronic and programmable electronic safety-related control systems. In addition, the increasingly common practice of using conformity assessment to demonstrate competence will be considered. 

Concurrent with the design activities for Darlington GS, Ontario Ify dro has undertaken a probabilistic safety study In order to provide a quantitative estimate of the safety of the plant. This study involves the development of fault tree models for failures of major process and safety systems. Because of the extensive use of programmable controllers in these systems. It became necessary to develop fault tree models for various failures of the PCs. 

So, from the general comments above, the electromagnetic environment seems to be able to play an important complex role for PES safety. The experimental work now presented deals with the programmable controller with respect to the other subsystems, its EM susceptibility takes most specifically the problem. 

This Section summarizes results of an experimental work performed at the Institut National de Recherche et de Securite about EMI effects on the safety of PES subsystems, f.i. industrial programmable controllers (IPC). These IPGs, which are a kind of PE, are considered as components and sold as such. A measurement campaign was performed in 1983 on 37 IPC s (5), and a second campaign in 1985 on 45 IPC s (6). All together, 23 of the world biggest manufacturers were represented. 

Intricated with a programmable logical one. Both of these technologies can be EM susceptible, but likely nor in the same manner nor with the same effects. In addition, programmable sequential control can behave specifically when submitted to EMI. Experimentally, the results of EMI tests performed on world marketed programmable controllers show ein important percentage still suffering of safety related malfunctions, in spite of recent improvements. 

Part of the overall safety relating to the equipment under control (EUC) and the EUC control system which depends on the correct functioning of the electrical/electronic/programmable electronic safety-related systems, other technology safety-related systems and external risk reduction facilities. 

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