12.2 Interlocking Sequence
The fan interlocking operates as follows:
1. Each IPD powers up with the FID output turned off. At this point the FIR input on all IPD Relays
will read, as off, therefore no outlet will run.
2. When a machine is plugged into an outlet that has its Remote Termination Unit programmed
“iFan” then that relay will be allowed to run when requested (provided there are no protection
trips, stops etc preventing its operation).
3. When that outlet is running and the current is above the preselected current threshold, a 5
second time delay is initiated. At the completion of this delay, that IPD Relay turns on its FID
output. The fan current threshold is adjustable from 32% to 96% of full load current in 8%
increments (See Section 13, User Adjustable Settings).
4. Detecting the interlocking signal via their FIR inputs then enables all other IPD Relays on the FIO
link.
5. If at any stage the fan current drops below the threshold, or the fan is stopped, the master IPD
Relay turns off the FID output. This causes all slave IPD Relays to stop.
If fan interlocking is not required, the system can be disabled by connecting a 10kΩ 1W resistor from the
FIO Terminal (Terminal 9) to 0V (Terminal 12) on each relay. In this case the FIO Terminals are not
interlinked. This causes the FIR inputs to read high at all times.
An auxiliary fan being used in this situation would have its Remote Termination Unit programmed with
machine type “Fan”.
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