Rosslare AC-825IP - Page 27

Figure 25: Normally Open Supervised Input (Single Resistor)
4.1.4. Normally Open 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 Open Supervised Input has 3 states:
•
Switch Open – Normal State:
Loop resistance = 10.4 kΩ
•
Switch Closed – Abnormal State:
Loop resistance = 2.2 kΩ
•
Open circuit (infinite loop resistance) or short circuit (0 resistance) across input terminals – Trouble State
Figure 26: Normally Open Supervised Input (Double Resistor)
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)
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