47
Fig. 8 — Outdoor Fan Staging Sequence for Design Series 4 units
WITHOUT OPTION
20-35 Ton
Contactor OFM(s)
Software Board Conrolled Controlled
Common CONDFANA MBB Rly 6 OFC1 OFM1 Any compressor ON
Common CONDFANB MBB Rly 5 OFC2 OFM2
# of Fans ON
Fans ON
Stage 1 OFC1 1 OFM1
Stage 2 OFC1,2 2 OFM1,2
Stage 2 if OAT > 75
Stage 2 if SCTA or STCB > HPSP
Stage down if SCTA/B < HPSP - 20 for two minutes and OAT < 73
WITH GREENSPEED/LOWAMBIENT OPTION
20-35 Ton
Contactor OFM(s)
Software Board Conrolled Controlled
Common OV_ENA LEN n/a OFM1 & 2 Any compressor ON, speed via GS_A_VFD
# of Fans ON
Fans ON
Stage GS 2 OFM1,2
Start with GS_VFD at 50% when OAT<70F , otherwise at 100%
Stage 1 if OAT > 60F, Follows equation; SCT set point = C1 + C2
* circuit capacity percent + C3 * OAT
Stage 2 if OAT < 60F, Maintains SCT at 100°F or User input (LAS
P)
Circuit
Controlling Output
Logic
Circuit A & B
If either of the SCT sensors has failed, then the control defaults to control based on the OAT sensor and set GS_VFD at
100% when the ambient is above 65°F and set GS_VFD at 50% when
the ambient temperature is below 50°F. Set a linear
function of SCT between 50 and 65°F OAT.
If the SCT and OAT sensors have all failed then the control run
GS_VFD @ 100% when any compressor is on.
If either of the SCT sensors has failed, then the control defau
lts to control based on the OAT sensor and turns on
CONDFANB when the ambient is above 65 dF and off when the ambient temperature is below 50 dF. If the SCT and OAT
sensors have all failed then the control turns on CONDFANB when any compressor is on.
LogicCircuit
Controlling Output
Circuit A & B
OFM
1
OFM
2
GS
GS
WITHOUT OPTION
36-50 Ton
Contactor OFM(s)
Software Board Conrolled Controlled
Common
CONDFANA MBB Rly 6 OFC1 OFM1,2
Common CONDFANB MBB Rly 5 OFC2 OFM3,4
# of Fans ON
Fans ON # of Fans ON Fans ON
Stage 1 OFC1 2 OFM1,2 Stage 1 OFC1 2 OFM1,2
Stage 2 OFC1,2 4 OFM1,2,3,4 Stage 2 OFC1,2 4 OFM1,2,3,4
Stage 2 if OAT > 75
Stage 2 if SCTA or STCB > HPSP
Stage down if SCTA/B < HPSP -
20
for two minutes and OAT < 73
WITH GREENSPEED/LOWAMBIENT OPTION
36-50 Ton
Contactor OFM(s)
Software Board Conrolled Controlled
A OV_ENA LEN n/a OFM 1 & 3 Any Circuit A compressor ON, speed via G
S_A_VFD
B OV_ENA LEN n/a OFM 2 & 4 Any Circuit B compressor ON, speed via GS_B_VFD
# of Fans ON
Fans ON # of Fans ON Fans ON
Stage GS 2 OFM1,3 Stage GS 2 OFM2,4
Start with GS_VFD at 50% when OAT<70F , otherwise at 100%
Stage 1 if OAT > 60F, Follows equation; SCT set point = C1 + C2 * circuit capacity percent + C3 * OAT
Stage 2 if OAT < 60F, Maintains SCT at 100°F or User input (LAS
P)
Circuit A
Circuit B
If the SCT sensor has failed, then the control defaults to control based on the OAT sensor and set corresponding circuit GS_VFD at
100% when the ambient is above 65°F and set GS_VFD at 50% when
the ambient temperature is below 50°F. Set a linear function o
SCT between 50 and 65°F OAT.
If the SCT and OAT sensors have all failed then the control run the corresponding GS_VFD @ 100% when any compressor is on th
specific circuit.
If either of the SCT sensors has failed, then the control defaults to control based on the OAT sensor and turns on CONDFANB when
the ambient is above 65 dF and off when the ambient temperature is below 50 dF. If the SCT and OAT sensors have all failed then
the control turns on CONDFANB when any compressor is on.
Circuit A
Circuit B
Circuit
Controlling Output
Logic
Circuit
Controlling Output
Logic
Any compressor ON
GS_A
1
GS_B
GS_B
2
GS_A
OFM_A
1
OFM_A
OFM_B
2
OFM_B4
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