Auto. Restart After Power Failure; Fast Power Source Transfers; Water/Brine Reset - Carrier AquaEdge 19XRV series Operation, Maintenance And Installation Manual

TOWER FAN HIGH SETPOINT (SETPOINT menu, default
75 F [23.9 C]).
The TOWER FAN RELAY HIGH is turned off when the
condenser pump is off, flow is stopped, or the EVAPORATOR
REFRIG TEMP is less than the EVAP REF OVERRIDE TEMP
and ENTERING CONDENSER WATER is less than 70 F
(21.1 C), or the difference between EVAPORATOR PRES-
SURE and CONDENSER PRESSURE is less than 28 Psid
(193 kPa), and ENTERING CONDENSER WATER tempera-
ture is less than TOWER FAN HIGH SETPOINT minus 3 F
(–16.1 C).
The TOWER FAN RELAY LOW and TOWER FAN RELAY
HIGH parameters are accessed from the STARTUP screen.
IMPORTANT: A field-supplied water temperature control
system for condenser water should be installed. The system
should maintain the leaving condenser water temperature at
a temperature that is at least 20 F (11 C) above the leaving
chilled water temperature. While the tower fan relay outputs
described above are not a substitute for a complete con-
denser water control system, they can serve as useful inputs
to such a system.
Auto. Restart After Power Failure — ICVC
Software Version 9 —
interruptable power supply installed.) The Auto. Restart feature
is enabled/disabled in the SETUP3 screen. Faults that will reset
when Auto. Restart is enabled are single cycle dropout (if en-
abled); ICVC Power On Reset; line current imbalance; high line
voltage; low line voltage; Power On Reset; low DC bus voltage;
high DC bus voltage; SIO comm loss with gateway; comm loss
between gateway and DPI board. With this feature enabled,
these faults are treated as alerts instead of alarms, so start-up pro-
ceeds as soon as the condition is rectified. The 15-minute start-
to-start and 1-minute start inhibit timers are both ignored during
this type of start-up, and the STARTS IN 12 HOURS counter is
not incremented.
The Auto. Restart feature allows the controls to make an ex-
press restart. When Auto. Restart is enabled, at the time of pow-
er up, if the chiller had been operating at the time of shutdown,
the controls will immediately energize the CHILLED WATER
PUMP output, wait 1 second, energize the CONDENSER WA-
TER PUMP output, then wait 1 second to start to verify water
flow. When flow is verified, and the chilled water temperature is
calling for cooling, the guide vane is checked for closure. Be-
cause the unit has VFD, the guide vanes have no closure require-
ment. For units with split ring diffusers, the diffuser position is
adjusted based on the GUIDE VANE / SRD FACTOR config-
ured in the SETUP3 screen. The lower this factor, the more
closed the SRD will be at restart.
The oil pump is then started, and when the oil pressure is con-
firmed, the controls wait 20 seconds to maintain pressure. At
this point the compressor is commanded to start.
If the Auto. Restart after Power Failure feature is enabled, the
chiller has a fast restart feature for any time the chiller starts.
This feature will use the same times as when the chiller starts af-
ter a power failure, but will not use the modification to VFD
speed or SRD (split ring diffuser) positioning.
(Applies to chillers without un-
Whenever power is restored, if power to the ICVC module
has been off for more than 3 hours or the timeclock has been set
for the first time, the compressor starts with the slowest tempera-
ture-based ramp load rate possible in order to minimize oil
foaming. The oil pump is energized occasionally during the time
the oil is being brought up to proper temperature in order to
eliminate refrigerant that has migrated to the oil sump during the
power failure. The pump turns on for 30 seconds at the end of
every 30-minute period until the chiller is started.
When the VFD is started and ramping to speed, the VFD start
speed is compensated for changes due to high gas torque levels.
The GAS TORQUE FACTOR in SETUP3 is used to modify
start speed. The higher the factor, the more the VFD is slowed
during restart to help prevent VFD overload.
Fast Power Source Transfers —
cal system is being prepared to transfer power from generator
power back to utility power or vice-versa, and the power trans-
fer is an open transition type, and time to transfer is less than 5
seconds, the chiller should be stopped before the transfer oc-
curs and restarted after the transfer has been completed. If the
chiller is not stopped before the transfer occurs, alarms on the
chiller can occur that must be manually reset, such as a circuit
breaker trip.
To accomplish shutdown and restart automatically, a set of
dry contacts should be opened 30 to 60 seconds before the
transfer occurs, then closed after the transfer is complete to re-
start the chiller. The contacts must be wired to the Remote
START/STOP contact in the starter or VFD (see the field wir-
ing diagrams) and the Remote Start contact configuration must
be enabled.
If power transfers take 5 seconds or longer, the chiller Auto.
Restart after Power Failure feature (if enabled) will automati-
cally restart the chiller.
Water/Brine Reset —
gle Cycle Dropout in the VFD configuration for this type of op-
eration. Chilled water capacity control is based on achieving
and maintaining a CONTROL POINT temperature, which is
the sum of the LCW SET POINT or ECW SETPOINT (from the
SETPOINT screen) and a Water/Brine Reset value, if any.
CONTROL POINT is limited to a minimum of 35 F (+1.7 C)
for water, or 10 F (–12.2 C) for brine. Three types of chilled
water or brine reset are available and can be viewed or modi-
fied on the TEMP_CTL screen, which is accessed from the
EQUIPMENT SERVICE table.
The ICVC default screen indicates when the chilled water
reset is active. TEMPERATURE RESET on the MAINSTAT
screen indicates the amount of reset. The CONTROL POINT
will be determined by adding the TEMPERATURE RESET to
the SETPOINT.
To activate a reset type, access the TEMP_CTL screen and
input all configuration information for that reset type. Then,
input the reset type number (1, 2, or 3) in the SELECT/
ENABLE RESET TYPE input line.
RESET TYPE 1: 4 TO 20 MA (1 TO 5 VDC) TEMPERA-
TURE RESET — Reset Type 1 is an "automatic" reset utiliz-
ing a 4 to 20 mA or 1 to 5 vdc analog input signal provided
from any external sensor, controller, or other device which is
appropriately configured. Reset Type 1 permits up to ±30 F
(±16.7 C) of reset to the chilled water set point. Inputs are
wired to terminals J5-3 (–) and J5-4 (+) on the CCM (for 4-20
mA input). In order to utilize a 1 to 5 vdc input, a 250-ohm
resistor must be wired in series with the + input lead (J5-4).
For either input type, SW2 DIP switches should be set in the
ON (up) position. Inputs equivalent to less than 4 mA result in
no reset, and inputs exceeding 20 mA are treated as 20 mA.
53
When the electri-
It is recommended to enable Sin-