Lenze 8400 motec Manual - Manual (Page 103)

Safety engineering
Basics for safety sensors
8
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103 EDS84DG752 EN 4.0
8.3 Basics for safety sensors
Passive sensors
Passive sensors are two−channel switching elements with contacts. The connecting cables
and the sensor function must be monitored.
The contacts must switch simultaneously (equivalently). Nevertheless, safety functions
will be activated as soon as at least one channel is switched.
The switches must be wired according to the closed−circuit principle.
Examples of passive sensors:
ƒ Door contact switch
ƒ Emergency−off control units
Active sensors
Active sensors are units with 2−channel semiconductor outputs (OSSD outputs). With the
integrated safety system of this device series, test pulses < 1 ms for monitoring the
outputs and cables are permissible. The maximally permissible connection capacity of the
outputs is to be observed.
P/M−switching sensors switch the positive and negative cable or the signal and ground
wire of a sensor signal.
The outputs have to switch simultaneously. Nevertheless, safety functions are triggered
as soon as at least one channel is switched.
Examples of active sensors:
ƒ Lightgrid
ƒ Laser scanner
ƒ Control systems