BS PD ISO/TR 24119:2015

BS PD ISO/TR 24119:2015 illustrates and explains principles of fault masking in applications where multipleinterlocking devices with potential free contacts (B1 to Bn) are connected in series to one logic unit(K) which does the diagnostics (see Figures 1 to 7). It further provides a guide how to estimate theprobability of fault masking and the maximum DC for the involved interlocking devices. This TechnicalReport only covers interlocking devices in which both channels are physical serial connections.This Technical Report does not replace the use of any standards for the safety of machinery.The goals of this Technical Report are the following:

• guidance for users for estimation of the maximum DC values;
• design guidance for SRP/CS.

NOTE 1 Interlocking devices with integrated self-monitoring are not included in the scope of this TechnicalReport.NOTE 2 Limitation is also given by the diagnostic means implemented in the logic unit.NOTE 3 This Technical Report is not restricted to mechanical actuated position sensors.Cross References:ISO 12100ISO 13849-1:2006ISO 14119:2013ISO 13849-2:2012 ISO 10218-2IEC 60204-1:2005