Specifications

49
The TOWER FAN RELAY LOW and TOWER FAN RELAY
HIGH parameters are accessed from the STARTUP screen.
Auto. Restart After Power Failure — This option
may be enabled or disabled and may be viewed or modified
on the OPTIONS screen, which is accessed from the
EQUIPMENT CONFIGURATION table. If the AUTO
RESTART OPTION is enabled, the chiller will start up automati-
cally after a power failure has occurred, generating one of the
following faults: single cycle dropout (if enabled), line current
imbalance, high line voltage, low line voltage, low DC bus
voltage, high DC bus voltage, VFD power on reset, and ICVC
power on reset (alerts 143-148, 165, and 166). With this feature
enabled, these faults are treated as alerts instead of alarms, so
start-up proceeds as soon as the condition is rectified. The 15
and 1-minute start inhibit timers are ignored during this type of
start-up, and the STARTS IN 12 HOURS counter is not
incremented.
When power is restored after the power failure and if the
compressor had been running, the oil pump will energize
for one minute before energizing the cooler pump. AUTO
RESTART will then continue like a normal start-up.
If power to the ICVC module has been off for more than
3 hours or the timeclock has been set for the first time, start the
compressor with the slowest TEMP PULLDOWN DEG/MIN
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 elimi-
nate 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.
Fast Power Source Transfers — When the the elec-
trical system is being prepared to transfer power from genera-
tor power back to utility power or vice-versa, and the power
transfer is an open transition type, and time to transfer is less
than 5 seconds, the chiller should be stopped before the transfer
occurs 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 cir-
cuit 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 automat-
ically restart the chiller.
Water/Brine Reset — 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 modified 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) TEMPERATURE
RESET — Reset Type 1 is an “automatic” reset utilizing a 4 to
20 mA or 1 to 5 vdc analog input signal provided from any
external sensor, controller, or other device which is appropri-
ately configured. Reset Type 1 permits up to ±30 F (±16.7 C)
of reset to the chilled water set point. Inputs are wired to termi-
nals 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.
RESET TYPE 2: REMOTE TEMPERATURE RESET —
Reset Type 2 is an automatic chilled water temperature reset
based on a remote temperature sensor input signal. Reset type 2
permits ± 30 F (± 16 C) of automatic reset to the set point based
on a temperature sensor wired to the CCM module (see wiring
diagrams or certified drawings). The temperature sensor must
be wired to terminal J4-13 and J4-14. To configure Reset Type
2, enter the temperature of the remote sensor at the point where
no temperature reset will occur (REMOTE TEMP –> NO RE-
SET). Next, enter the temperature at which the full amount of
reset will occur (REMOTE TEMP –> FULL RESET). Then,
enter the maximum amount of reset required to operate chiller
(DEGREES RESET). Reset Type 2 can now be activated.
RESET TYPE 3 — Reset Type 3 is an automatic chilled water
temperature reset based on cooler temperature difference.
Reset Type 3 adds ± 30 F (± 16 C) based on the temperature
difference between the ENTERING CHILLED WATER and
LEAVING CHILLED WATER temperature.
To configure Reset Type 3, enter the chilled water tempera-
ture difference (the difference between entering and leaving
chilled water) at which no temperature reset occurs (CHW
DELTA T –> NO RESET). This chilled water temperature dif-
ference is usually the full design load temperature difference.
Next, enter the difference in chilled water temperature at which
the full amount of reset occurs (CHW DELTA T –> FULL RE-
SET). Finally, enter the amount of reset (DEGREES RESET).
Reset Type 3 can now be activated.
Surge Prevention — A surge condition occurs when the
lift becomes so high that the gas flow across the impeller re-
verses. This condition can eventually cause chiller damage.
The surge prevention algorithm notifies the operator that chiller
operating conditions are marginal and to take action to help
prevent chiller damage such as lowering entering condenser
water temperature.
The surge prevention algorithm is an operator-configurable
feature that can determine if lift conditions are too high for the
compressor and then take corrective action. Lift is defined as
the difference between the saturated temperature at the impeller
eye and at the impeller discharge. The maximum lift a particu-
lar impeller wheel can perform varies with the gas flow across
the impeller and the size of the wheel.
Variable Primary Flow Surge prevention is the current stan-
dard for both constant and variable primary flow chilled water
systems. Variable Primary Flow Surge Prevention does not re-
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 leav-
ing chilled water temperature.
CAUTION
The tower fan relay control is not a substitute for a con-
denser water temperature control. When used with a water
temperature control system, the tower fan relay control can
be used to help prevent low condenser water temperatures.