IEC 60947-5-6 Ed. 1.0 b:1999, Low-voltage switchgear and controlgear - Part 5-6: Control circuit devices and switching elements - DC interface for proximity sensors and switching amplifiers (NAMUR)

Applies to proximity sensors connected for operation by a two-wire connecting cable to the control input of a switching amplifier. The switching amplifier contains a d.c. source to supply the control circuit and is controlled by the variable internal resistance of the proximity sensor. These devices can be used in an explosive atmosphere if they also comply with IEC 60079-11.