Carrier AquaEdge 23XRV - PIC III System Functions; Capacity Control; Forced

45
Table 3 — ICVC Display Data (cont)
EXAMPLE 28 — RAMP_DEM DISPLAY SCREEN
To access this display from the ICVC default screen:
1. Press .
2. Press .
3. Scroll down to highlight .
4. Press .
5. Scroll down to highlight .
NOTE: No variables are available for CCN read or write operation.
EXAMPLE 29 — TEMP_CTL DISPLAY SCREEN
To access this display from the ICVC default screen:
1. Press .
2. Press .
3. Scroll down to highlight .
4. Press .
5. Scroll down to highlight .
PIC III System Functions
NOTE: Words not part of paragraph headings and printed in all
capital letters can be viewed on the ICVC (e.g., LOCAL,
CCN, RUNNING, ALARM, etc.) Words printed in both all
capital letters and italics can also be viewed on the ICVC and
are parameters (CONTROL MODE ADDED EXAMPLES,
etc.) with associated values (e.g., modes, temperatures, pres-
sures, percentages, on, off, enable, disable, etc.). Words printed
in all capital letters and in a box represent softkeys on the
ICVC (e.g., and ). See Table 3 for examples of
the type of information that can appear on the ICVC screens.
Figures 24-30 give an overview of ICVC operations and
menus. The sequence of screens that should be selected to
view any parameter in the ICVC can be found in Appendix A.
CAPACITY CONTROL — The PIC III control system con-
trols the chiller capacity by changing the compressor speed in
response to chilled liquid temperature deviation away from the
CONTROL POINT. The CONTROL POINT may be changed
by a CCN network device or is calculated by the PIC III
control adding any active chilled liquid reset to the ECL or LCL
SET POINT. The CONTROL POINT may be viewed or over-
ridden from the MAINSTAT screen. See Fig. 27.
Changes to the chiller capacity and system overrides are
achieved through the VFD SPEED OUTPUT.
The VFD SPEED OUTPUT is controlled by varying the
output from 0 to 100%. The TARGET VFD SPEED is forcible
and allows the operator manual control of the VFD SPEED
OUTPUT. The TARGET VFD SPEED will be allowed to
change every five seconds unless TARGET VFD SPEED is
forced.
The TARGET VFD SPEED is controlled between the VFD
MINIMUM SPEED and VFD MAXIMUM SPEED (refer to
SETUP2 screen) based on the Capacity Control algorithm. The
PIC III controls monitor the compressor oil properties and set a
COMP MINIMUM SPEED to ensure sufficient compressor
bearing lubrication under all operating conditions. The TAR-
GET VFD SPEED shall not be allowed to be forced below the
COMP MINIMUM SPEED. A summary of all capacity control
conditions and responses is shown in Table 4.
MENU
SERVICE
EQUIPMENT SERVICE
SELECT
RAMP_DEM
DESCRIPTION STATUS UNITS POINT DEFAULT
Pulldown Ramp Type:
0/1
ramp_opt
1
Select: Temp=0, KW=1
Demand Limit and kW Ramp
Demand Limit Source 0/1 dem_src 0
Select: Amps=0, kW=1
Amps or kW Ramp %/Min 5 to 20 kw_ramp 10
Demand Limit Prop Band 3 to 15 % dem_app 10
Demand Limit At 20 mA 40 to 100 % dem_20ma 40
20 mA Demand Limit Opt 0/1 DSABLE/ENABLE dem_sel DSABLE
VFD Overload Decrease 25 to 50 % vfd_dec 30
VFD Overload Delta 3 to 15 % vfd_delt 5
Demand Watts Interval 5 to 60 MIN dw_int 15
DESCRIPTION STATUS UNITS POINT DEFAULT
Control Point Source
ECL Control Option 0/1 DSABLE/ENABLE ecl_opt DSABLE
Temp Pulldown Ramp/Min 2 to 10 (1.1 to 5.6) ^F (^C) tmp_ramp 3 (1.7)
Temperature Reset
RESET TYPE 1
Degrees Reset At 20 mA –30 to 30 (–17 to 17) ^F (^C) deg_20ma 10 (6)
RESET TYPE 2
Remote Temp –> No Reset –40 to 245 (–40 to 118) °F (°C) res_rt1 85 (29)
Remote Temp –> Full Reset –40 to 245 (–40 to 118) °F (°C) res_rt2 65 (18)
Degrees Reset –30 to 30 (–17 to 17) ^F (^C) deg_rt 10 (6)
RESET TYPE 3
CHL Delta T –> No Reset 0 to 15 (0 to 8) ^F (^C) restd_1 10 (6)
CHL Delta T –> Full Reset 0-15 (0 to 8) ^F (^C) restd_2 0 (0)
Degrees Reset –30 to 30 (–17 to 17) ^F (^C) deg_res 5 (3)
Enable Reset Type 0 to 3 res_sel 0
MENU
SERVICE
EQUIPMENT SERVICE
SELECT
TEMP_CTL
ENTER
EXIT