Chiller Shutdown Sequence; Refrigerant Lubrication Control; Control Points - Carrier AquaEdge 19DV Controls Operation And Troubleshooting

Fig. 30 — Start-Up Sequence Screen
Table 12 — Pre-Start Alerts and Alarms
PRE-START ALERT
CONDITION
STARTS IN 12 HOURS >= 8
CONDENSER PRESSURE >=
COND PRESS OVERRIDE – 20 psi
Number of recycle restart in the last 4 hours
is greater than 5
COMP BEARING TEMP >= COMP BEAR-
ING ALERT – 10°F (5.5°C)
COMP MOTOR WINDING TEMP >=
MOTOR TEMP OVERRIDE – 10°F (5.5°C)
COMP DISCHARGE TEMP >= COMP DIS-
CHARGE ALERT– 10°F (5.5°C)
EVAP_SAT < Evap trip point* +
EVAP OVERRIDE DELTA T
or
EVAP REFRIG LIQUID TEMP < Evap trip
point* + EVAP OVERRIDE DELTA T
ACTUAL LINE VOLTAGE <=
UNDERVOLTAGE THRESHOLD
ACTUAL LINE VOLTAGE >=
OVERVOLTAGE THRESHOLD
Guide vane 1 has not been calibrated
successfully
Prestart Failure - No Power Supply (If Water
Verification Time has passed after Request
To Start has been sent and there has not
been received a Permission To Start)
Guide vane 2 has not been calibrated
successfully
* Evap trip point = 33°F (0.6°C) (water) or EVAP REFRIG TRIPPOINT
(brine).

Chiller Shutdown Sequence

Chiller shutdown begins if any of the following occurs:
• Local OFF button is pressed
• A recycle condition is present (see the previous section)
• The time schedule has gone into unoccupied mode when in
either Network or Local Schedule control mode
• The chiller protective limit has been reached and chiller is
in alarm
• The start/stop status (CHIL_S_S) is overridden to stop
from the network when in Network mode
If the chiller is normally shut down from running, a soft-stop
shutdown will be performed. The soft-stop feature closes the
guide vanes of the compressor automatically if a non-alarm
stop signal occurs before the compressor motor is deenergized.
Any time the compressor is directed to STOP (except in the
cases of a fault shutdown), the guide vanes are directed to close
and VFD will be commanded to minimum speed for a variable
speed compressor. The compressor shuts off when any of the
following is true:
When any of these conditions is true, the shutdown sequence
stops the compressor by deactivating the compressor start re-
lay. The guide vanes are then commanded to the fully closed
position. The refrigerant pump relay will be turned off after
120 seconds post-lube.
Finally, the chilled water/brine pump and condenser water
pump are shut down.

Refrigerant Lubrication Control

As part of the pre-lube process, the Bearing Input Refrigerant
Pressure is compared to the Bearing Output Refrigerant Pressure.
If the Bearing Input Refrigerant Pressure (BRGI_P) is less than 5
psi (34.5 kPa) higher than the Bearing Output Refrigerant Pressure
STATE ALARM OR
(BRGO_P), the liquid level in the condenser is checked. If the liq-
NO. ALERT
uid level switch is ON, refrigerant is pumped from the evaporator
100 Alert
to the condenser until the liquid level switch is OFF. Once the con-
denser liquid level is satisfied, the Evaporator Temperature
102 Alert
(EVAP_T) is compared to the Leaving Condenser Water Tem-
perature. When the Evaporator Temperature is 10 degrees higher
103 Alert
than the Leaving Condenser Water Temperature or the Refrigerant
Lubrication Pressure Difference is at least 12 psi, the refrigerant
230 Alarm
pump remains on the compressor is turned ON.
231 Alarm
The refrigerant pump relay is always ON when the compressor
is running.
232 Alarm

Control Points

SET POINT
233 Alarm
The set point can be configured at the Setpoint menu ("USER"
access level).
234 Alarm
The set point is determined by the heat/cool mode, EWT (en-
tering water temperature) option, and ice build option. See
235 Alarm
Table 13.
236 Alarm
237 Alarm
238 Alarm
NOTES:
CONTROL POINT TEMPERATURE
Capacity control is based on achieving and maintaining a con-
trol point temperature, which is the sum of a valid set point
(from the SETPOINT screen) and a temperature reset value. In
Cooling mode, the control point temperature is equal to the set
point plus temperature reset. In Heating mode, the control
point temperature is equal to the set point minus temperature
reset.
The control point can be viewed directly on the main screen or
the General Parameters menu.
TEMPERATURE RESET
Three types of chilled water or brine reset are available and can
be viewed or modified on the Reset Configuration screen.
17
• PERCENT LOAD CURRENT (%) drops below the SOFT
STOP AMPS THRESHOLD
• ACTUAL GUIDE VANE POSITION drops below 4%
• Four minutes have elapsed since the stop was initialized
Table 13 — Set Point Determination
EWT
CONTROL
COOLING
OPTION
Disabled Cooling LCW Set Point
Enabled Cooling ECW Set Point
1. The ice build option is disabled when heat/cool mode is set to
Heating.
2. When the ice build option is enabled and ice build is active, the
control point is the Ice Build Set Point and the controlled water tem-
perature is the leaving chilled water temperature.
HEAT/COOL MODE
HEATING
Heating LCDW Set Point
Heating ECDW Set Point