7EN02-0423-02

Examples of application of preventive alarm relay mirroring modes

When the device is inoperative, the system should automatically switch to another device by managing exclusions using the injection inhibition input. See Injection inhibition input (Inhibit. Input) for more information on injection inhibition input.

Set the preventive insulation alarm relay to mirror mode and wire the relays in series to create a logical AND function. It is advised to configure the insulation alarm relay in failsafe mode and wire both relays in (NC/C). In this case, the logical function returns true only when the device is inoperative or de-energized, or when a special status is active.

The following wiring diagram is an example of the device wired in standard mode:

Mode Input State
No fault Preventive alarm Alarm Inoperative product No power
Standard PLC 1 1 1 1 0 0
Standard PLC 2 1 1 0 0 1

The following wiring diagram is an example of the device wired in failsafe mode:

Mode Input State
No fault Preventive alarm Alarm Inoperative product No power
Failsafe PLC 1 0 0 0 1 1
Failsafe PLC 2 0 0 1 1 1

ALARM=(RelayState:ON) || ((StatusInput:CLOSED) & (RelayState:OFF))

  • An insulation alarm is detected when both PLC inputs are at a logic 1.

  • A product failure is detected when PLC input 1 is a logic 0.

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