EN 50227:1997

Foreword
1 Scope
2 Normative references
3 Definitions
4 Classification
5 Characteristics
6 Product information
7 Normal service, mounting and transport conditions
8 Constructional and performance requirements
9 Tests
Figure 1 Example of a continuous characteristic of a
           proximity sensor
Figure 2 Example of discontinuous characteristic of a proximity
           sensor
Figure 3 Control input of the switching amplifier
Figure 4 Characteristics of proximity sensor in the high
           impedance state
Figure 5 Characteristics of proximity sensor in the low
           impedance state
Table 1 Classification of proximity switches
Table 2 Connection and wiring identification

This standard applies to proximity sensors connected for operation by a two-wire connecting conductor 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. Note 1. These devices can be used in an explosive atmosphere if they also comply with EN 50020 "Electrical equipment for explosive atmospheres and intrinsic safety 'i'". 2. These devices have been defined by the German organization "Normenausschuss für Mess-und Regelungstechnik (NAMUR)"