Siemens SIPART PS2 6DR50xx Instrucciones de operaciones descargar pdf (Pagina 228)

Appendix

A.3 Test report (extract)

SIPART PS2 with and without HART communications

228 Operating Instructions, 09/2007, A5E00074631-07

Stephan Aschenbrenner Page 4 of 4

The assessment has shown that the Electro-pneumatic Positioner SIPART PS2 when

used as a single-acting shut-down module ("tight closing bottom") has a PF D

AV G

within

the allowed range for SIL 2 according to table 2 of IEC 61508-1 and table 3.1 of ANSI/ISA–

84.01–1996 and a Safe Failure Fraction (SFF) of more than 84%. Based on the verification

of "proven-in-use" according to IEC 61508 and its direct relationship to “prior-use” of

IEC 61511-1 it can be used as a single device for SIL2 Safety Functions in terms of

IEC 61511-1 First Edition 2003-01.

The failure rates listed above do not include failures resulting from incorrect use of the Electro-

pneumatic Positioner SIPART PS2, in particular humidity entering through incompletely closed

housings or inadequate cable feeding through the inlets.

The listed failure rates are valid for operating stress conditions typical of an industrial field

environment similar to IEC 60654-1 class Dx (outdoor location) with an average temperature

over a long period of time of 40ºC. For a higher average temperature of 60°C, the failure rates

should be multiplied with an experience based factor of 2,5. A similar multiplier should be used

if frequent temperature fluctuation must be assumed.

A user of the Electro-pneumatic Positioner SIPART PS2 can utilize these failure rates in a

probabilistic model of a safety instrumented function (SIF) to determine suitability in part for

safety instrumented system (SIS) usage in a particular safety integrity level (SIL). A full table of

failure rates for different operating conditions is presented in section 5.2 to 5.5 along with all

assumptions.

It is important to realize that the “no effect” failures and the “annunciation” failures are included

in the “safe undetected” failure category according to IEC 61508. Note that these failures on its

own will not affect system reliability or safety, and should not be included in spurious trip

calculations.

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Siemens SIPART PS2 6DR50xx Instrucciones de operaciones Pagina 228