K Phillipson

Data

Data, information, formulae, constants and the like ....
references to useful websites - the best
some select data

EN 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e. tools, dust, fingers) and moisture

What is IEC61508? IEC 61508 is the international standard for electrical, electronic and programmable electronic safety related systems. It sets out the requirements for ensuring that systems are designed, implemented, operated and maintained to provide the required safety integrity level (SIL). Four SILs are defined according to the risks involved in the system application, with SIL4 being applied for the highest risks. The standard specifies a process that can be followed by all links in the supply chain so that information about the system can be communicated using common terminology and system parameters. Other standards are being produced for the application of the 61508 approach to particular sectors. IEC 61511 relating to the process industries has recently been published. Safety Integrity Levels (SILs) are a safety-measurement standard defined by several bodies including the International Electro technical Commission in IEC 61508 to quantify the chance of dangerous failures in electrical or electronic safety devices, that is, the probability of the device to fail in performing its safety function. See also Defence Standard 00-56 Issue 2 for another implementation of SILs. Four SIL levels are possible, with SIL4 being the most dependable and SIL1 being the least. For example, for Safety Instrumented Systems acting in low demand mode, the SIL level depends on the average PFD (probability of failure upon demand) as: SIL Probability of failure on-demand % Reliable 1 0.1 to 0.01 (10-2 to 10-1) (90-99%) 2 0.01 to 0.001 (10-3 to 10-2) (99-99.9%) 3 0.001 to 0.0001 (10-4 to 10-3) (99.9-99.99%) 4 0.0001 (10-5 to 10-4) (>99.99%) SIL is defined and calculated according to IEC 61508 and other sector-specific standards like IEC 61511, IEC 62061 or ISA S84.01. Important parts of the safety lifecycle are determining the safety functions required (SIFs) for a process, the target SIL for each one (based on the necessary risk reduction factor), and the design of the Safety Instrumented System to comply with the requested SIL. Electric and electronic devices can be certified for use in SIL applications of a given SIL level according to IEC 61508, thus providing the market with some degree of confidence in their safety performance and with a means of determine if they can be used in a given application.