Carrier NDK33BN0KB, Operation & Service Manual

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62-61753-21 2-9
2.4 CONDENSING SECTION
The condensing section (see Figure 2-1) consists of
an engine-generator drive package, compressor,
economizer heat exchanger, condenser fans, conden-
ser/radiator coil, refrigerant controls, defrost air switch,
piping, wiring, and associated components.
The engine-generator drive package (see Figure 2-2)
includes the engine, generator, air cleaner, muffler,
coolant system, fuel system, oil filter system and en-
gine sensors.
2.4.1 Engine
The engine is a four cylinder diesel which gives excel-
lent fuel economy and has easy starting characteris-
tics. It is equipped with spin-on lube oil and fuel oil
filters for easier filter changes. The engine cooling
system consists of the radiator (which is integral with
the condenser coil) and coolant overflow bottle. The
system is also fitted with an electronic battery charger
which converts generator or standby alternating cur-
rent to direct current for battery charging. Refer to
Section 2.8 for engine data.
2.4.2 Engine Air System
The air cleaner prolongs the life and performance of
the engine by preventing dirt and grit from getting into
the engine and causing excessive wear on all operat-
ing parts. It is the responsibility of the operator to give
the air cleaner equipment regular and constant atten-
tion in accordance with the instructions. (Refer to sec-
tion 8.4.8)
2.4.3 Engine Switches, Transducers and Sensors
a. Engine Speed Sensor (ENRPM)
The ENRPM provides the microprocessor with engine
speed information to be displayed, recorded in the
Data Recorder and used to control the refrigeration
system. It is located on the front of the engine near the
generator.
b. Engine Oil Pressure Switch (ENOPS)
The ENOPS is normally open and closes on pressure
rise to signal to the microprocessor the engine
has sufficient oil pressure for operation. There is a 15
second delay after the engine starts to allow the oil
pressure to build up before the microprocessor looks
at the input from this switch. The switch is located on
the gear case cover.
c. Engine Coolant Temperature Sensor (ENCT)
The ENCT provides microprocessor with engine cool-
ant temperature information to be displayed, recorded
in the Data Recorder and used to control the refrigera-
tion system. The sensor is located on the starter side
of the engine near the #4 Injector.
2.4.4 Generator (GEN)
The generator is directly bolted to the engine and sup-
plies nominal 460V/3Ø/60Hz power when the engine is
in high speed and nominal 300V/3Ø/45Hz power in
low speed.
2.4.5 Compressor
The unit is fitted with a scroll compressor equipped
with suction and discharge service valves and an
economizer connection. The compressor draws refrig-
erant gas from the evaporator and delivers it to the
condenser at an increased temperature and pressure.
The pressure is such that refrigerant heat can be ab-
sorbed by the surrounding air at ambient tempera-
tures.
2.4.6 Compressor Switches, Transducers and
Sensors
a. Compressor Discharge Pressure Transducer
(CDP)
The CDP provides a signal to the microprocessor
equivalent to pressure leaving the compressor. It is
located on the discharge line above the compressor.
b. Compressor Suction Pressure Transducer
(CSP)
The CSP provides a signal to the microprocessor
equivalent to pressure entering the compressor suc-
tion service valve. It is located on the suction service
valve.
c. Compressor Discharge Temperature Sensor
(CDT)
The CDT provides a signal to the microprocessor
equivalent to the temperature of the gas leaving the
compressor. It is located on the upper dome of the
compressor.
d. Compressor Suction Temperature Sensor (CST)
The CST provides a signal to the microprocessor
equivalent to to the temperature of the gas entering
the compressor suction service valve. It is located on
the line entering the valve.
e. High Pressure Switch (HP1)
The HP1 is normally closed and opens on pressure
rise to signal to the microprocessor to shut down the
engine or shut down the system if operating on
standby power. It is located on the discharge service
valve.
2.4.7 Unloader Solenoid Valve (USV)
The USV is opened, during periods of low load, to
bypass a portion of the compressed gas from the
economizer connection to the suction service valve.
This action balances compressor capacity with the
load and results in lower power consumption.
2.4.8 Liquid Injection Solenoid Valve (LIV)
The LIV is opened, during periods high compressor
discharge temperature to inject refrigerant into the
economizer connection to cool the compressor.
2.4.9 Condenser Coil
The condenser coil is of the tube in fin type and acts
as a heat exchanger in which the compressed refrig-
erant gas is condensed into a liquid and lowered in
temperature. Air movement over the condenser is
provided by two electric motor driven fans mounted in
the condensing section.