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2.2 Vapor Temperature Limits
Any application of screw compressors must operate within
the limits defined by the application maps for the various re-
frigerants and applications.
Vapor Temp
Suction
Economizer
*SH = Superheat
**The maximum economizer pressure allowable is 175.3 psig
(13.1 bar)
2.3 Minimum Oil Pressure Differential
A minimum pressure differential of 45 psi (3 bar) is required
between suction and oil pressure (at the compressor). Ap-
plications below this minimum range will require the use of
an external oil pump.
2.4 Variable Speed Operation
The Carlyle screw compressor is compatible with variable
speed drives, the table below shows the allowable speed
range.
Carlyle does not recommend the screw compressor operate
at maximum frequency for prolonged periods of time.
Operation above 60 Hz requires adequate motor cooling.
When overspeeding, there will be an increased power con-
sumption required to supply the additional capacity. This will
also increase the required motor cooling load. It is important
that the motor cooling system be capable of handling the in-
creased cooling required for the motor. Oil return, econo-
mizer return gas, and the motor cooling valve all assist in
cooling the motor. Carlyle recommends applying the largest
motor cooling valve with all screw compressors applied us-
ing inverters.
R-22 APPLICATIONS
Min.
Max.
10°F SH*
100°F
(6K)
(38°C)
Saturated**
—
Vapor
Compressors should ramp-up to the minimum speed within
15 seconds at start-up. After compressor start, Carlyle rec-
ommends that the rate of compressor speed change be lim-
ited to 600 rpm/min for the 06T semi-hermetic compressors.
The rate of compressor speed change for the 05T open-
drive models is required to be no greater than 500 rpm/min.
Compressor
Nominal
Model
HP
06T—033
15
06T—039
20
06T—044
20
06T—048
25
06T—054
25
06T—065
30
06T—078
35
06T—088
40
06T—108
50
15
05T—033
30
20
05T—039
35
20
05T—044
40
05T—048
25
05T—054
25
*Open Motor Type applies to 05T models only.
2.5 Compressor Cycling
Although compressor cycling is an effective means of ca-
pacity control, frequent starting and stopping shortens the
compressor life. Carlyle screw compressors should not be
stop/start cycled for capacity control more than six times an
hour and should run for at least 5 minutes after each start.
Min.
Max.
Open Motor
Hz
Hz
Type*
50
70
—
40
70
—
35
70
—
30
70
—
30
70
—
25
70
—
20
68
—
20
60
—
20
50
—
50
140
4-POLE
25
70
2-POLE
40
140
4-POLE
20
70
2-POLE
35
120
4-POLE
20
60
2-POLE
20
70
4-POLE
20
70
4-POLE
7
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