Rosslare AC-425 - Normally Closed Supervised Single EOL Resistor Input Connection; Normally Closed Supervised Double EOL Resistor Input Connection; Figure 14: Normally Closed Supervised Input (Single Resistor)

Input and Output Connections
AC-425 Hardware Installation and User Manual 23
4.1.5 Normally Closed Supervised Single EOL Resistor Input
Connection
Connect a 2.2 kΩ resistor in series to the input switch contacts.
A Normally Closed Supervised Input has 3 states:
 Switch Closed – Normal State:
Loop resistance = 2.2 kΩ
 Switch Open – Abnormal State:
Loop resistance = Infinite (open circuit)
 Short circuit across input terminals – Trouble State:
Loop resistance = 0 (short circuit)
Figure 14: Normally Closed Supervised Input (Single Resistor)
4.1.6 Normally Closed Supervised Double EOL Resistor Input
Connection
Connect a 2.2 kΩ resistor in series to the input switch contacts.
Connect an 8.2 kΩ resistor parallel to the input switch contacts.
A Normally Closed Supervised Input has 3 states:
 Switch Closed – Normal State:
Loop resistance = 2.2 kΩ
 Switch Open – Abnormal State:
Loop resistance = 10.4 kΩ
 Open circuit (infinite loop resistance) or short circuit (0 resistance) across
input terminals – Trouble State