the exhaust temperature spread monitor is enabled automatically in the logic.
during startup,acceleration and load selection the exhaust temperature spread monitor has a bias added to allow for transients.
if there is high spread at full speed (for instance if a can flames out) the unit will trip on high spread.
thermal stabilization of the unit has nothing to do with the spreads.
thermal stabilization of the unit is defined by the rate of change of the interstage temperatures (wheelspace thermocouples), usually: less than 2degF in 15min
high exhaust spread is related to combustion or exhaust thermocouple problems.
the unit could be in transient thermal state (wheelspace temperature changing) and still have a high spread condition and trip.
conversely... the unit could have high wheelspace temperatures (in alarm) due to damaged sealing and no spread.
Your spread will likely change with load, and the position of the highest and lowest readings will also be affected due to the change in "swirl". That is what I meant in an earlier post when I talked about allowing the readings to stabilize after a load change.
If a can flames out at no-load, put some load on it to increase the compressor discharge pressure. This may be enough to allow the unit to cross-fire between cans and re-light the flame-out.
P