Specifications

81
2. If ACTUAL GUIDE VANE POSITION is still less than
30 and step 1 failed, then increase the value of SURGE
LINE SHAPE FACTOR in steps of 0.01 up to 2 times.
For example, if surge is encountered when shape factor is
–0.06, increase the SURGE LINE SHAPE FACTOR to
–0.05. If this does not solve the problem, go to step 5,
even if ACTUAL GUIDE VANE POSITION is less than
30%.
3. Do not change SURGE LINE SHAPE FACTOR from
the value selected by Chiller Builder (ECAT). Decrease
SURGE/HGBP DELTA TSMAX by 1°F Steps up to 5
times. Monitor chiller for surge.
4. If ACTUAL GUIDE VANE POSITION is greater than
60% and Step 4 failed to eliminate surge, then set
SURGE/HGBP DELTA TSMAX to 5° F below the value
specified by Chiller Builder (ECAT). Increase the value
of the SURGE LINE SHAPE FACTOR in steps of 0.01
up to 2 times. For example, if surge is encountered when
the SURGE LINE SHAPE FACTOR is –0.06, increase
the SURGE LINE SHAPE FACTOR to –0.05. If this
does not solve the problem, go to Step 5, even if ACTU-
AL GUIDE VANE POSITION is greater than 60%.
5. If ACTUAL GUIDE VANE POSITION is greater than
30% but less than 60% or if Step 2 failed (with ACTUAL
GUIDE VANE POSITION less than 30) or if Step 4
failed (with ACTUAL GUIDE VANE POSITION great-
er than 60), then perform this step. Do not change
SURGE LINE SHAPE FACTOR from the value speci-
fied by Chiller Builder (ECAT). Reset SURGE/HGBP
DELTA TSMIN and SURGE/HGBP DELTA TSMAX to
the value specified by Chiller Builder (ECAT). Decrease
SURGE/HGBP DELTA TSMIN and SURGE/HGBP
DELTA TSMAX in steps of 1° F up to 5 times. Monitor
chiller for surge.
CONFIGURE DIFFUSER CONTROL IF NECES-
SARY — If the compressor is equipped with a variable
diffuser, (size 4 or 5 compressor) access the SETUP2 screen.
Scroll to DIFFUSER CONTROL and press the
softkey. Compare the diffuser and guide vane values (GUIDE
VANE 25% LOAD PT, GUIDE VANE 50% LOAD PT, GUIDE
VANE 75% LOAD PT, DIFFUSER 25% LOAD POINT,
DIFFUSER 50% LOAD POINT, DIFFUSER 75% LOAD
POINT) to the values located on the label inside the control
panel above the ICVC. See Fig. 11.
Compressors with variable diffuser control have actuators
tested and stamped with the milliamp (mA) value that results in
100% actuator rotation. In addition to the diffuser position
schedule, the DIFFUSER FULL SPAN mA of the split ring
diffuser actuator must be entered in the SETUP2 screen. This
information is printed on a label affixed under the solid state
controller box on the right side of the split ring diffuser actuator
when viewing the compressor from the suction end.
Units with VFD
— On units with VFD further adjustments can
be made if response to surge prevention or protection is not
functioning as desired. VFD GAIN and VFD INCREASE STEP
can be adjusted to allow for more aggressive changes in speed
when surge prevention or protection is active.
MODIFY EQUIPMENT CONFIGURATION IF NECES-
SARY — The EQUIPMENT SERVICE table has screens to
select, view, or modify parameters. Carrier’s certified drawings
have the configuration values required for the jobsite. Modify
these values only if requested.
EQUIPMENT SERVICE Screen Modifications
— Change
the values on these screens according to specific job data. See
the certified drawings for the correct values. Modifications can
include:
• Chilled water reset
• Entering chilled water control (Enable/Disable)
• 4 to 20 mA demand limit
• Auto restart option (Enable/Disable)
• Remote contact option (Enable/Disable)
See PIC II System Functions (page 40) for description of
these functions.
Owner-Modified CCN Tables
— The following EQUIP-
MENT CONFIGURATION screens are described for refer-
ence only.
OCCDEFCS — The OCCDEFCS screen contains the Local
and CCN time schedules, which can be modified here or on the
SCHEDULE screen as described previously.
HOLIDAYS — From the HOLIDAYS screen, the days of the
year that holidays are in effect can be configured. See the holi-
day paragraphs in the Controls section for more details.
BRODEF — The BRODEF screen defines the start and end of
daylight savings time. By default this feature is enabled (for
software versions 4.0 and later). Enter the dates for the start
and end of daylight savings if required for your location. Note
that for Day of Week, 1 represents Monday. Start Week and
Stop Week refer to the instance of the selected Day of Week
during the selected month and year. To disable the feature,
change START ADVANCE and STOP BACK times to 0
(minutes). In the BRODEF table the user may also identify a
chiller as the time broadcaster for a CCN network. There
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
55.00
60.00
0 10 20 30 40 50 60 70 80 90 100 110
Shape factor
= -0.020
Shape factor
= -0.040
Shape factor
= -0.050
GV_POS
Delta Tsat
Fig. 39 — Effect of SURGE LINE SHAPE FACTOR
on Surge Prevention
a19-1961
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
0 102030405060708090100110
Speed Factor
=1.60
Speed Factor
=1.85
Speed Factor
=2.00
GV_POS
Delta Tsat
Fig. 40 — Effect of SURGE LINE SPEED FACTOR
on Surge Prevention
a19-1962
ENABLE