Carrier 48/50AJ specifications Power Exhaust Staging BP.CF =

Table 83 — Power Exhaust Staging (BP.CF = 2)

BP.MT = 1 (4 motors)	PE.A	PE.B	PE.C
Power Exhaust Stage 0	OFF	OFF	OFF
Power Exhaust Stage 1	ON	OFF	OFF
Power Exhaust Stage 2	OFF	ON	OFF
Power Exhaust Stage 3	ON	ON	OFF
Power Exhaust Stage 4	ON	ON	ON

BP.MT = 2 (6 motors)	PE.A	PE.B	PE.C
Power Exhaust Stage 0	OFF	OFF	OFF
Power Exhaust Stage 1	ON	OFF	OFF
Power Exhaust Stage 2	OFF	ON	OFF
Power Exhaust Stage 3	ON	ON	OFF
Power Exhaust Stage 4	ON	OFF	ON
Power Exhaust Stage 5	OFF	ON	ON
Power Exhaust Stage 6	ON	ON	ON

•If building pressure (Pressures→AIR.P→BP) is less than the building pressure set point (Configuration→ BP→BPSP) minus the building pressure low threshold level (Configuration→BP→B.CFG→BP.LP) subtract a stage of power exhaust.

VFD POWER EXHAUST BUILDING PRESSURE CON- TROL (BP.CF = 3) — A 4 to 20mA analog output from Economizer Control Board 1 (ECB-1, AO1) is provided as a speed reference for a field-installed VFD power exhaust accessory. If building pressure (Pressures→AIR.P→BP) rises above the building pressure set point (BP.SP) and the supply fan is on, then building pressure control is initialized. Thereaf- ter, if the supply fan relay goes off or if the building pressure drops below the BP.SP minus the building pressure set point offset (BP.SO) for 5 continuous minutes, building pressure control will be stopped. The 5-minute timer will continue to re- initialize if the VFD is still commanded to a speed > 0%. If the building pressure falls below the set point, the VFD will slow down automatically. Control is performed with a PID loop where:

Error = BP – BP.SP

K = 1000 * BP.RT/60 (normalize the PID control for run rate)

P = K * BP.P * (error)

I = K * BP.I * (error) + “I” calculated last time through the

PID

D = K * BP.D * (error – error computed last time through the PID)

VFD speed reference (clamped between BP.MN and BP.MX%) = P + I + D

Smoke Control Modes — There are four smoke con- trol modes that can be used to control smoke within areas ser- viced by the unit: Pressurization mode, Evacuation mode, Smoke Purge mode, and Fire Shutdown. Evacuation, Pressur- ization and Smoke Purge modes require the Controls Expan- sion Board (CEM). The Fire Shutdown input is located on the main board (MBB) on terminals TB5-10 and 11. The unit may also be equipped with a factory-installed return air smoke de- tector that is wired to TB5-10 and 11 and will shut the unit down if a smoke condition is determined. Field-monitoring wiring can be connected to terminal TB5-8 and 9 to monitor the smoke detector. Inputs on the CEM board can be used to put the unit in the Pressurization, Evacuation, and Smoke Purge modes. These switches or inputs are connected to TB6 as shown below. Refer to Major System Components section on page 101 for wiring diagrams.

Pressurization — TB6-12 and 13 Evacuation — TB6-13 and 14

Smoke Purge — TB6-13 and 15

Each mode must be energized individually on discrete in- puts and the corresponding alarm is initiated when a mode is activated. The fire system provides a normally closed dry con- tact closure. Multiple smoke control inputs, sensed by the con- trol will force the unit into a Fire Shutdown mode.

FIRE-SMOKE INPUTS — These discrete inputs can be found on the local display under Inputs→FIRE.

ITEM	EXPANSION	RANGE	CCN	WRITE
			POINT	STATUS
FIRE	FIRE-SMOKE INPUTS
FSD	Fire Shutdown Input	ALRM/NORM	FSD	forcible
PRES	Pressurization Input	ALRM/NORM	PRES	forcible
EVAC	Evacuation Input	ALRM/NORM	EVAC	forcible
PURG	Smoke Purge Input	ALRM/NORM	PURG	forcible

Fire Shutdown Mode — This mode will cause an immediate and complete shutdown of the unit.

Pressurization Mode — This mode attempts to raise the pres- sure of a space to prevent smoke infiltration from an adjacent space. Opening the economizer (thereby closing the return air damper), shutting down power exhaust and turning the indoor fan on will increase pressure in the space.

Evacuation Mode — This mode attempts to lower the pres- sure of the space to prevent infiltrating an adjacent space with its smoke. Closing the economizer (thereby opening the return- air damper), turning on the power exhaust and shutting down the indoor fan decrease pressure in the space.

Smoke Purge Mode — This mode attempts to draw out smoke from the space after the emergency condition. Opening the economizer (thereby closing the return-air damper), turning on both the power exhaust and indoor fan will evacuate smoke and bring in fresh air.

AIRFLOW CONTROL DURING THE FIRE-SMOKE MODES — All non-smoke related control outputs will get shut down in the fire-smoke modes. Those related to airflow will be controlled as explained below. The following matrix specifies all actions the control shall undertake when each mode occurs (outputs are forced internally with CCN priority number 1 - “Fire”):

DEVICE	PRESSURIZATION	PURGE	EVACUATION	FIRE
				SHUTDOWN
Economizer	100%	100%	0%	0%
Indoor Fan —	ON/FSO*	ON/FSO*	OFF	OFF
VFD
Power Exhaust	OFF	ON/FSO*	ON/FSO*	OFF
Heat Interlock	ON	ON	OFF	OFF
Relay

*“FSO” refers to the supply VFD fire speed override configurable speed.

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