Unit Description
22
Sequence of Operation
The Zone 1/Host On/Off switch must be turned
On before any other zone will operate. When the
Zone 1/Host On/Off switch is turned On, the
backlight illuminates the display and the operating
icons appear. The unit will start automatically in
both Continuous Run and CYCLE-SENTRY
modes.
The microprocessor uses a complex program to
determine which operating mode each zone
should be in. Therefore, it is difficult to predict
which operating mode an evaporator should be in
by comparing its setpoint to the compartment
temperature. Also, the different versions of
software that are used have some operational
differences.
Each zone that is turned on will operate in one of
the following modes:
•
Cool
•
Heat
•
Defrost
•
Null
During engine operation, engine speed is
determined by a combination of the requirements
of each zone and the discharge pressure. The
diesel engine will operate in High or Low Speed
accordingly.
Defrost
Defrost is initiated automatically by the
microprocessor or manually by selecting defrost
from the Defrost Prompt Screen for the desired
zone. A Demand Defrost cycle will also occur
based on the return air temperature and discharge
air temperature or coil temperature. The
evaporator coil temperature must be below 45 F
(7 C) to allow defrost. When the Defrost Icon for
a zone appears, the damper door is closed or the
fans are turned off. Several defrost features are
programmable. The unit is designed to defrost in
low speed.
The zone will stay in defrost until the evaporator
coil temperature rises to 58 F (14 C). If the
evaporator coil temperature does not rise above
58 F (14 C) within the Defrost Duration (DDUR)
time limit, the microprocessor will terminate
defrost and display the Alarm Icon. The Defrost
Duration can be set for either 30 or 45 minutes.
System Operation
Several operating characteristics of the unit are:
•
All zones can cool at the same time.
•
All zones can heat at the same time.
•
Any zone can cool while any other zone heats.
•
When a zone is in null, the blowers may run
but the zone does not cool or heat.
•
When a zone is in heat while another zone is
in cool, the evaporator in the zone that is in
heat acts as the condenser.
•
The condenser inlet solenoid and the suction
line solenoids are normally open solenoid
valves that close when energized.
•
The liquid line solenoids, the hot gas
solenoids, the receiver tank pressure solenoid
and the purge valve are normally closed
solenoid valves that open when energized.
•
The flow of refrigerant through the system is
controlled by the solenoid valves and the
check valves.
•
If the condenser inlet solenoid is energized
(closed) because a zone is in heat or defrost,
and if the discharge pressure exceeds 400 psi
(2758 kPa), the condenser inlet solenoid is
de-energized until the discharge pressure
drops below 250 psi (1724 kPa).
•
The receiver tank pressure solenoid and the
purge valve are energized (open) when any
zone is in heat or defrost. If the discharge
pressure exceeds 300 psi (2068 kPa), the
receiver tank pressure solenoid and the purge
valve are de-energized until the discharge
pressure drops below 225 psi (1551 kPa).
•
During engine operation when all zones are in
cool, the microprocessor will shift the engine
to low speed if the discharge pressure exceeds
425 psi (2930 kPa). High speed is enabled, if
required, when the discharge pressure drops
below 375 psi (2586 kPa).
Summary of Contents for Spectrum DE 30-2
Page 4: ...4...
Page 12: ...Safety Precautions 12...
Page 16: ...Specifications 16...
Page 31: ...Unit Description 31 1 Access Panels 2 Defrost Dampers Figure 12 Back View of Unit 1 2 AGA215...
Page 42: ...Operating Instructions 42...
Page 48: ...Electrical Maintenance 48...
Page 106: ...Structural Maintenance 106...
Page 110: ...Mechanical Diagnosis 110...
Page 114: ...Remote Evaporator Specifications 114...
Page 116: ...Remote Evaporator Maintenance Inspection Schedule 116...
Page 122: ...Remote Evaporator Electrical Maintenance 122...
Page 126: ...Remote Evaporator Refrigeration Service Operations 126...
Page 128: ...Remote Evaporator Structural Maintenance 128...
Page 130: ...Remote Evaporator System Diagnosis 130...
Page 134: ...Wiring and Schematic Diagrams Index 134...
Page 135: ...135 Schematic Diagram Page 1 of 2...
Page 136: ...136 Schematic Diagram Page 2 of 2...
Page 137: ...137 Wiring Diagram Page 1 of 4...
Page 138: ...138 Wiring Diagram Page 2 of 4...
Page 139: ...139 Wiring Diagram Page 3 of 4...
Page 140: ...140 Wiring Diagram Page 4 of 4...