Falcon Lead Lag Appendix E
E-58
Stager Parameters
ADD-STAGE INTERSTAGE DELAY: MM:SS
This specifies the minimum time that the Stager waits after adding one stage before adding another stage or drop-
ping a stage.
DROP-STAGE INTERSTAGE DELAY: MM:SS
This parameter specifies the minimum time that the Stager waits after dropping one stage before dropping another
stage or adding a stage.
Functions common to all stager states
These functions handle overall burner demand responsibility, and take care of cleaning up any anomalous
conditions.
BURNER DEMAND
The stager checks the Master’s LL burner demand. If this demand is off all slaves with SlaveStates of AddStage,
SuspendStage, or Firing are set to Available by the Rate Allocator turning them all off and the StagerState is set to
be Idle.
STAGERSTATE = IDLE WITH SLAVES ACTIVE
If the stager runs and its state is Idle, it checks the status of all slaves. If any of these have SlaveState=AddStage,
SuspendStage, or Firing then these are set to Available (this will cause the Rate Allocator to turn them all off).
Stager States
The stager's operation is defined for each of its states:
STAGERSTATE = IDLE
Burner demand means that a demand source is calling for heat and there is also setpoint demand.
When there is no burner demand the stager is forced to be Idle.
When burner demand becomes true (Call for Heat) the stager checks the sequencer to identify the lead boiler. That
boiler is given a command to start.
The stager resets (to verify it is at 0) and starts its StagerTimer, and sets the StagerTimeLimit to the value of the
slave's Demand-to-firing delay time.
If the Stager fails to get even one boiler from the Sequencer, it issues an alert and suspends until it runs again.
STAGERSTATE = ADDSTAGERESPONSE
During this state the stager is waiting for slave to transition to Firing.
If the identified boiler has a SlaveState=Firing then the stager:
Resets and starts it’s StagerTimer, sets the StagerTimeLimit to Add-stage interstage delay, and changes the
StagerState to InterstageDelay.
If the boiler's SlaveState is still AddStage then:
The stager checks to see if the StagerTimer has reached the StagerTimeLimit.
If so then the stager: Changes the SlaveState to SuspendStage, resets and starts its StagerTimer, sets the Stager-
TimeLimit to T_StagerSuspend. This allows additional time for the slave to reach its firing condition.
STAGERSTATE = ADDSTAGESUSPEND
During this state the stager is waiting to see if the slave has transitioned to Firing or Available.
If the identified boiler has a SlaveState=Firing then the stager:
Resets and starts its StagerTimer, sets the StagerTimeLimit to Add-stage interstage delay, it changes the Stag-
erState to InterstageDelay.
The stager checks to see if the StagerTimer has reached the StagerTimeLimit.
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