www.miinet.com
Moore Industries-International, Inc.
- 70 -
User’s Manual
225-748-01L
February 2017
1oo2 Redundant Architecture
In this architecture, every component appears twice, and may be applicable for use in SIS
systems up to SIL 3 (Figure 8.3). Advantages are improved reliability of trip action and reduced
vulnerability to a single failure compared to a 1oo1 architecture. The logic in this configuration is
an ‘OR’ statement for the safety function; if either sensor input reaches a trip condition or a fault
relay is activated, the loop or function will reach a tripped state.
Figure 8.3
. The STA in a 1oo2 Redundant/Voting Architecture is Applicable for Use in SIS Systems Up to SIL 3.
NC1
CM1
NO1
NC2
CM2
NO2
NC3
CM3
NO3
NC1
CM1
NO1
NC2
CM2
NO2
NC3
CM3
NO3
Sensor Input 1
Sensor Input 2
Process
Trip 1
Process
Trip 2
Fault
Alarm
Process
Trip 1
Process
Trip 2
Fault
Alarm
Final Element/
Logic Solver
SELECT
DOWN
UP
COM
READY INPUT
TRIP 1 TRIP 2 FAULT
17.29
MA
STA
SAFETY
TRIP
ALARM
TAG
SELECT
DOWN
UP
COM
READY INPUT
TRIP 1 TRIP 2 FAULT
17.29
MA
STA
SAFETY
TRIP
ALARM
TAG
Programmable Current/Voltage Safety Trip Alarm
STA
HLPRG
SEC
TION 8