Safety Manual User Manual

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Document: 553630
ICSTT-RM446K-EN-P Issue: 10_C
4-13
Field Loop Circuit for Line Monitored Digital Input for Emergency Shutdown Systems (ESD)
The suggested values for R1 and R2 are as follows:
R1 = 15K 1%, 1W (maximum power dissipated is 47mW at 26.4V)
R2 = 3K9 1%, 1W (maximum power dissipated is 182mW at 26.4V)
Suggested threshold values for both of the above circuits are as follows:
Threshold ID Value (mV)
Maximum Allowed = 32000
SHORT CIRCUIT
Threshold 8 = 19000
Threshold 7 = 18500
ON (nominal 16V)
Threshold 6 = 11000
Threshold 5 = 10500
INDETERMINATE
Threshold 4 = 6500
Threshold 3 = 6000
OFF (nominal 8V)
Threshold 2 = 3500
Threshold 1 = 3000
OPEN CIRCUIT
Assumptions:
 Loop supply voltage = 24V ± 10%
 Maximum Field Cable Line Resistance: < 100  total; this means < 50 + 50
 for the two cables.