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58
Table 51B — Head Pressure/Fan Cycling Control (088 and 104 Sizes)
CONTROL OUTPUTS
LEGEND
UNIT CONFIGURATION
MOTOR
LOCATION
CIRCUIT:
MOTOR ID NO.
OFM ON
OFM OFF
Standard
(with standard SCT sensors)
(MMAS = Yes)
(TRNS = No)
First Stage
A: 1
B: 2
SCT > (HPSP – 15 F)
SCT < (HPSP – 37 F)
for 90 secs AND
Second Stage motors OFF
Second Stage
A: 3, 5
B: 4, 6
SCT > HPSP
(start delayed 60 secs after
start of compressor, unless
SCT > 143 F)
SCT < (HPSP – 35 F) for two
minutes
With Accessory Sensors
(Pressure Transducers
and Suction Thermistors)
(MMAS = Yes)
(TRNS = Yes)
(SUSN = Yes)
First Stage
A: 1
B: 2
SCT > 138 F
SCT < (HPSP – 37 F) for 90
secs AND
Second Stage motors OFF
Second Stage
A: 3, 5
B: 4, 6
SCT > HPSP
(start delayed 60 secs after
start of compressor, unless
SCT > 143 F)
SCT < (HPSP – 35 F)
for two minutes AND
superheat greater than
30 F for two minutes
Motormaster® Disabled
(MMAS = No)
First Stage
A: 1
B: 2
On with compressor
Off with compressor
Second Stage
A: 3, 5
B: 4, 6
SCT > HPSP
SCT < (HPSP – 35 F)
for two minutes
MOTOR GROUP/CIRCUIT
CHANNEL
RELAY
CONTACTOR
First Stage/A
PSIO2 47
MMR-A
MMC-A
First Stage/B
PSIO2 46
MMR-B
MMC-B
Second Stage/A
DSIO1 29
—
OFC-A
Second Stage/B
DSIO2 30
—
OFC-B
DSIO
— Relay Module
HPSP
— Head Pressure Set Point
MMC
— Motormaster® Contactor
MMR
— Motormaster Relay
OFC
— Outdoor-Fan Contactor
OFM
— Outdoor-Fan Motor
PSIO
— Processor Module
SCT
— Saturated Condensing Temperature