Specifications

40
The TOWER FAN RELAY LOW and 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 SERVICE
table. If the AUTO. RESTART option is enabled, the chiller
will start up automatically after a power failure has occurred
(after a single cycle dropout; low, high, or loss of voltage; and
the power is within ±10% of normal). The 15 and 3-minute
inhibit timers are ignored during this type of start-up.
When power is restored after the power failure, a power
failure restart will be enabled and the control allowed to
AUTORESTART the chiller, starting with the chilled liquid
pump(s), if start-up conditions are met.
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 will start with the slowest temperature-based ramp
load rate possible in order to minimize oil foaming.
Liquid/Brine Temperature Reset — Three types of
chilled liquid or brine setpoint temperature 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 liquid
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 ECL SETPOINT or LCL 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 (0 to 5 vdc) TEMPERATURE
RESET — Reset Type 1 is an automatic chilled liquid tempera-
ture reset based on a remote temperature sensor input config-
ured for either an externally powered 4 to 20 mA or a 0 to
5 vdc signal. Reset Type 1 permits up to ±30 F (±17 C) of
automatic reset to the ECL SETPOINT or LCL SETPOINT.
The auto, chilled liquid reset is hardwired to CCM terminals
J5-3 (–) and J5-4 (+). Switch setting number 2 on SW2 will
determine the type of input signal. With the switch set at the
ON position the input is configured for an externally powered
4 to 20 mA signal. With the switch in the OFF position the
input is configured for an external 0 to 5 vdc signal. One of the
following modifications are also required when using a 1 to
5 vdc temperature reset signal:
1. Install a 25 ohm resistor in series with the (+) voltage
lead connected to CCM terminal J5-4.
2. Modify the input voltage signal with an external con-
troller software to calibrate the temperature interpreted
by the CCM. The controller should provide 4.54 v at
100% of the controller’s output range and 0.91 v at 0%
of the controller’s output range.
RESET TYPE 2: REMOTE TEMPERATURE RESET —
Reset Type 2 is an automatic chilled liquid temperature reset
based on a remote temperature sensor input signal. Reset Type
2 permits ±30 F (±17 C) of automatic reset to the ECL
SETPOINT or LCL SETPOINT based on a temperature sensor
wired to the CCM module (see wiring diagrams or certified
drawings). The temperature sensor must be wired to CCM
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 RESET). Next, enter the
temperature at which the full amount of reset will occur
(REMOTE TEMP -> FULL RESET). Then, enter the maxi-
mum amount of reset required to operate the chiller
(DEGREES RESET). Reset Type 2 can now be enabled.
RESET TYPE 3 — Reset Type 3 is an automatic chilled liquid
temperature reset based on the difference between ENTER-
ING CHILLED LIQUID and LEAVING CHILLED LIQUID
temperature. Reset Type 3 adds ±30 F (±17 C) based on the
chilled liquid temperature difference.
To configure Reset Type 3, enter the chilled liquid tempera-
ture difference (the difference between entering and leaving
chilled liquid) at which no temperature reset occurs (CHL
DELTA T -> NO RESET). This chilled liquid temperature
difference is usually the full design load temperature
difference. Next, enter the difference in chilled liquid tempera-
ture at which the full amount of reset occurs (CHL DELTA T ->
FULL RESET). Finally, enter the amount of temperature reset
(DEGREES RESET). Reset Type 3 can now be enabled.
Demand Limit Control Option — The demand limit
control option (20 mA DEMAND LIMIT OPT) is externally
controlled by a 4 to 20 mA or 1 to 5 vdc signal from an energy
management system (EMS). The option is set up on the
RAMP_DEM screen. When enabled, 4 mA is the 100%
demand set point with an operator-configured minimum
demand at a 20 mA set point (DEMAND LIMIT AT 20 mA).
The auto. demand limit is hardwired to terminals J5-1 (–)
and J5-2 (+) on the CCM. Switch setting number 1 on CCM
SW2 will determine the type of input signal. With the switch
set at the ON position the input is configured for an externally
powered 4 to 20 mA signal. With the switch in the OFF posi-
tion the input is configured for an external 1 to 5 vdc signal.
One of the following modifications are also required when us-
ing a 1 to 5 vdc DEMAND LIMIT signal:
1. Install a 25 ohm resistor in series with the (+) voltage
lead connected to CCM terminal J5-2.
2. Modify the input voltage signal with an external con-
troller software to calibrate the temperature interpreted
by the CCM. The controller should provide 4.54 v at
100% of the controller’s output range and 0.91 v at 0%
of the controller’s output range.
Hot Gas Bypass (Optional) Algorithm (See
Fig. 22A, 22B, and 23) —
If a hot gas bypass solenoid
valve is present and the HGBP OPTION in the OPTIONS ta-
ble is set to 1 or 2, this operator configurable feature can deter-
mine if load conditions are too low for the compressor and cor-
rective action can be taken.
When the HGBP OPTION = 0: the HGBP algorithm is
disabled.
When the HGBP OPTION = 1, the algorithm determines if
corrective action is necessary by checking the chiller operating
point against an operator configured threshold. The threshold is
calculated from a combination of the difference between Enter-
ing and Leaving Chilled Liquid temperatures and the differ-
ence between CONDENSER PRESSURE and EVAPORA-
TOR PRESSURE. The operator configured data points are the
MIN LOAD POINT(T1/P1) and the FULL LOAD POINT
(T2/P2). These points have default settings defined in the
OPTIONS screen and on Table 3. A line is drawn between
these points as shown in Fig. 22A and 22B. The default Load
Points (to prevent compressor stall) are shown. Whenever the
IMPORTANT: A field-supplied liquid temperature control
system for condenser liquid should be installed. The sys-
tem should maintain the leaving condenser liquid tempera-
ture at a temperature that is 20º F (11º C) above the leaving
chilled liquid temperature.
CAUTION
The tower fan relay control is not a substitute for a con-
denser liquid temperature control. When used with a liquid
temperature control system, the tower fan relay control can
be used to help prevent low condenser liquid temperatures.