Rockwell Automation Publication ICSTT-RM448J-EN-P - April 2018
105
Install the AADvance System
Chapter 5
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:
Assumptions:
• Loop supply voltage = 24V ± 10%
• Maximum Field Cable Line Resistance: < 100
total; this means < 50
+ 50
for the two cables.
• Minimum Isolation is 0.75M
between the field loop conductors.
• These values will allow the input to detect more accurately different
voltage levels that represent OPEN CCT - OFF - ON - SHORT CCT
and will also detect Over Voltage and an input which is neither ON nor
OFF. The values ensure that a line fault will be declared before it
becomes possible for a false declaration of On and Off states due to a
combination of resistor value drift and loop voltage variation.
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
