Carlyle 06ZCE1H3AA06013, Application Manual

Page: 9 / 24

9
Environmental Considerations
OPERATING AMBIENT TEMPERATURE
The screw compressor is designed for the following ambient tem-
perature ranges:
Non-Operating:
–40°F to 176°F (–40°C to 80°C)
Operating: –31°F to 131°F (–35°C to 55°C)
SALT-SPRAY REQUIREMENTS
The compressor has been tested through 500 hours of salt-spray in
compliance with ASTM specification B-117.
Operating Limits and Controls
The following operating envelopes show where the compressor
can be operated in both direct expansion and flooded applications
(see Fig. 5).
AIR-COOLED CONDENSING WITH R-134A, R-1234ZE,
OR R-513A FULL LOAD OPERATING ENVELOPE WITH
LIQUID INJECTION
Fig. 5 — Full Load Operating Envelope with Liquid
Injection
START-UP AND SUCTION PRESSURE TRANSIENTS
Operating a screw compressor without refrigerant flow through
the compressor can be harmful. When this occurs, the evaporator
typically will go into a vacuum, leading to very high pressure ra-
tios and little mass flow to carry the heat away from the screw ro-
tors. This situation most often occurs during start-up when the
refrigerant may be in another part of the system. This is tolerable
for short periods of time. The compressor should not be al-
lowed to operate with a suction pressure less than 0 psig (vac-
uum) for more than 1 minute after a “cold” start. If a com-
pressor is allowed to operate for longer periods of time without
refrigerant flow, catastrophic damage to the screw rotors, rotor
housing, and discharge housing may occur, requiring compres-
sor replacement.
OIL SUPPLY TEMPERATURE TO COMPRESSOR
To reduce the possibility of liquid refrigerant becoming entrained
in the oil, it is recommended that the temperature of the oil enter-
ing the compressor is kept above the outdoor ambient as shown in
Fig. 6 and Table 2.
Fig. 6 — Oil Temperature
COMPRESSOR ROTATION CONTROL
Correct compressor rotation is one of the most critical application
considerations. Powered reverse rotation, even for a very short du-
ration, can seriously affect the reliability of the compressor.
The reverse rotation protection scheme must be capable of deter-
mining the direction of rotation and stopping the compressor with-
in 1 second. Reverse rotation is most likely to occur at initial start-
up or whenever the wiring to the compressor terminals is
disturbed.
To minimize the possibility for reverse rotation operation, Carlyle
recommends the following procedures:
1. During initial run test of the unit, a suitable low pressure
switch should be temporarily installed on the high-pressure
port of the compressor and be wired to open the compressor
control circuit. The purpose of this switch is to protect the
compressor against any wiring errors at the compressor ter-
minal pins. The electrical contacts of the switch must be
wired in the control circuit of the compressor start compo-
nents to shut off the compressor in the event it is operating in
reverse rotation. This switch would remain in place for the
duration of the run test. At the end of the run test the switch
would be removed so that it could be used on the next unit or
compressor to be tested.
2. For service replacement compressors, a similar protection
system is recommended. The unit service literature will make
reference to this switch and provide instructions on how to
temporarily install the low-pressure switch into the safety cir-
cuit for the compressor. Each service compressor will be sup-
plied with Installation Instructions documenting the
procedure for installing and using the switch. The switch will
remain in place until the compressor has been started and
direction of rotation has been verified; at this point the switch
will be removed.
R-1234ze
–22 –13 –4 5 14 23 32 41 50 59 68
Saturated Suction Temperature (°F)
Saturated Discharge T
emperature (°C)
Saturated Discharge T
emperature (°F)
Saturated Suction Temperature (°C)
–30 –25 –20 –15 –10 –5 0 5 10 15 20
80
70
60
50
40
30
20
10
176
158
140
122
104
86
68
50
Full Load Envelope R-1234ze
Liquid
Injection < 30%
Suction Mass
Flow
Table 2 — Allowable Temperature Ranges
CONTROL
POINT
MINIMUM MAXIMUM
Discharge
Gas
20°F (11°C)
superheat
210°F (99°C)
Economizer
Gas
Saturated
Liquid
9°F (5°C) superheat
Suction Gas Saturated Vapor
10°F superheat. Best for
low discharge tempera-
tures
Oil Supply at
Compressor
Refer to Fig. 6 210°F (99°C)
Motor
Windings
No limit 275°F (135°C)
Min D
e
lt
a Oil Te
m
p
>
A
m
bien
t (
ºF)
Mi
n D
e
lt
a
Oil T
e
mp
>
Am
b
ie
n
t (ºC)
Outdoor Ambient Temperature [OAT] (°C)
-18 -7 4 16 27 38
25
20
15
10
5
0
0 20 40 60 80 100
Outdoor Ambient Temperature [OAT] (°F)
14
12
10
8
6
4
2
0