It was always my understanding that the primary reason 7EA load tunnel temperature was monitored was in order to protect the Bently-Nevada proximitor cables from heat damage. I seem to recall that temperature was around 350 deg F; check the documentation on the B-N website for certainty. I seem to recall that some units even had cooling and sealing air "injected" into the conduit/junction box for cooling the cable(s) when the unit was running (check the Cooling and Sealing Air Piping Schematic drawing).
The problem with the load tunnel temperature sensor arrangement is that many times when the units are shut down (and there's no cooling air flowing in the load compartment) the alarm is annunciated. Without cooling air flowing in the load compartment when the unit is shut down from loaded operation, the temperature does increase, but there's little one can do about the temperature increase unless cooling air can be circulated.
When are you experiencing the alarm: When the unit is running, or when it's shut down? If it's when the unit is shut down, describe the cooling air system for circulating cooling air in the load compartment on your unit. If it's when the unit is running, then you may have an exhaust leak in the load tunnel.
We are a MKVI 7EA site. Not sure if control constant naming is different, I find LTKALM set at 430 degf. Hope this helps. Note we had a large exhaust leak into the load compartment of one of our turbine due to broken seal bolts, but we never got to alarm temps.
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