Historical
IEC 60947-5-3 Ed. 1.0 b:1999
Low-voltage switchgear and controlgear - Part 5-3: Control circuit devices and switching elements - Requirements for proximity devices with defined behaviour under fault conditions (PDF)
Applies to proximity devices with an enhanced resistance to failure (PDF) It specifies requirements for four different types of PDF.
International Electrotechnical Commission [iec]