Safety Function - GE RSTi-EP Functional Safety Manual

System Overview
The RSTi-EP safe power-feed modules EP-19xx are intended for
connecting safety-related equipment. The EP-19xx modules are
controlled using contact-based safety transducers and/or safety
transducers with OSSD inputs. The safety function consists of the safe
disconnection of 24 V outputs by switching them Off when there is a
safety circuit failure.
Each EP-19xx module safely switches off all following modules that
are supplied by the output current path and thus creates a safety
segment. A survey of the switchable modules is shown at the end of
this section. The safety segment extends either to the next EP-7641
module or to the end of the station. A safety-related input circuit
together with pulsed inputs is used for detecting broken wires and
short circuits.
In the RSTi-EP system, three types of EP-19xx modules are available:
•
EP-1901 (one safe input)
•
EP-1902 (two safe inputs)
•
EP-1922 (two safe inputs, delayed switching off possible)
With EP-19xx modules, the following safety functions can be
implemented:
•
Up to two dual-channel safety circuits (AND linked), for
example, for emergency stop switch, safety door contacts and
safety light curtain
•
A range of output modules within a RSTi-EP station is safely
supplied with power via the switched 24 V Safe output.
•
EP-19xx modules can be cascaded.
3.1

Safety Function

The safety function of the safe power-feed modules is that the safe
output 24 V Safe is being switched according to the information of the
inputs (Type 3 according to EN 61131-2, N-switching respectively). The
safe status is 24 V switched off (current path for outputs and the
output 24 V Safe is switched off).
GFK-2956A November 2017
Chapter3. System Overview
Safe Power-feed Module EP-1901
Safe Power-feed Module EP-1902
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