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Fig. 18 — High Pressure/SCT Alarm Upper Envelope
T076 (Outside Air Relative Humidity Sensor Failure)
Failure of this sensor (
Inputs
REL.H
OA.RH
) will disable
any elements of the control which requires its use. Elements of
failure include: economizer outdoor and differential enthalpy
control. Recovery from this alert will be automatic. Reason for
error is either a faulty sensor, wiring error or damaged input on
the CEM control board.
T077 (Space Relative Humidity Sensor Failure)
Failure of this sensor (
Inputs
REL.H
SP.RH
) will disable
any elements of the control which requires its use. Elements of
failure include humidification and dehumidification. Recovery
from this alert is automatic. Reason for error is either a faulty
sensor, wiring error, or damaged input on the CEM control
board.
T078 (Return Air Relative Humidity Sensor Fail)
Failure of this sensor (
Inputs
REL.H
RA.RH
) will disable
any elements of the control which requires its use. Elements of
failure include economizer differential enthalpy control, hu-
midification, and dehumidification. Recovery from this alert is
automatic. Reason for error is either a faulty sensor, wiring er-
ror, or damaged input on the CEM control board.
T082 (Space Temperature Offset Sensor Failure)
When this failure occurs, there is no offset available that may
be applied to space temperature. Recovery from this alert is
automatic. Reason for error is either a faulty slider
potentiometer, wiring error, or damaged input on the MBB
control board.
T090 (Circ A Discharge Press Transducer Failure)
T091 (Circ B Discharge Press Transducer Failure)
The associated circuit becomes disabled whenever this trans-
ducer (
Pressures
REF.P
DP.A, DP.B
) fails. Recovery from
this alert is automatic. Reason for error is either a faulty sensor,
wiring error, or damaged input on the MBB control board.
T092 (Circ A Suction Press Transducer Failure)
T093 (Circ B Suction Press Transducer Failure)
The associated circuit becomes disabled whenever this trans-
ducer (
Pressures
REF.P
SP.A, SP.B
) fails. Recovery from
this alert is automatic. Reason for error is either a faulty sensor,
wiring error, or damaged input on the MBB control board.
T110 (Circuit A Loss of Charge)
T111 (Circuit B Loss of Charge)
Alert codes 110 and 111 are for circuits A and B respectively.
These alerts occur when all the compressors on a circuit are
OFF and the suction pressure is less than 18 psig, if the OAT is
above –5°F for 1 continuous minute. The alert will automati-
cally clear when the suction pressure transducer reading is val-
id and greater than 54 psig. The cause of the alert is usually
low refrigerant pressure or a faulty suction pressure transducer.
P120 (Circuit A Low Saturated Suction Temp. Comp Shutdown)
T120 (Circuit A Low Saturated Suction Temperature Alert)
A120 (Circuit A Low Saturated Suction Temperature Alarm)
P121 (Circuit B Low Saturated Suction Temp. Comp Shutdown)
T121 (Circuit B Low Saturated Suction Temperature Alert)
A121 (Circuit B Low Saturated Suction Temperature Alarm)
This alert/alarm is used to keep the evaporator coils from freez-
ing and the saturated suction temperature above the low limit
for the compressors.
When
Temperatures
REF.T
SST.A
or
Temperatures
REF.T
SST.B
is less than 20°F for 4 minutes, less than 10°F
for 2 minutes, less than 0°F for 1 minute, or less than –20°F for
20 seconds continuously, a compressor of the affected circuit
will be shut down with a local pre-alert (P120, P121) and a 15-
minute timeguard will be added to the compressor. If the saturat-
ed suction temperature continues to be less than 20°F for 4 min-
utes, less than 10°F for 2 minutes, less than 0°F for 1 minute, or
less than –20°F for 20 seconds continuously, another compressor
of the affected circuit, if it exists, will be shut down with a local
pre-alert (P120, P121) and a 15-minute timeguard will be added
to the compressor. This sequence will continue until the last
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
-30
-20
-10
0
10
20
30
40
50
60
70
80
SST (F)
SD
T (
F
)
Summary of Contents for Weathermaster 48P2030-100
Page 130: ...130 Fig 19 Typical Power Schematic Sizes 040 075 Shown ...
Page 131: ...131 Fig 20 Main Base Board Input Output Connections ...
Page 132: ...132 Fig 21 RXB EXB CEM SCB Input Output Connections ...
Page 133: ...133 Fig 22 Typical Gas Heat Unit Control Wiring 48P030 100 Units Shown ...
Page 134: ...134 Fig 23 Typical Electric Heat Wiring 50P030 100 Units Shown ...
Page 135: ...135 Fig 24 Typical Power Wiring 115 V ...
Page 136: ...136 Fig 25 Typical Gas Heat Section Size 030 050 Units Shown ...
Page 138: ...138 Fig 27 Component Arrangement Size 030 035 Units ...
Page 139: ...139 Fig 28 Component Arrangement Size 040 075 Units ...
Page 140: ...140 Fig 29 Component Arrangement Size 090 100 Units ...