Specifications

39
Spare Alarm Contacts — One normally open trip
alarm contact is provided in the control center cabinet. The
contact ratings are provided in the certified drawings. The
contacts are located on terminals 9 and 10 of the hazardous
voltage terminal strip in the control center cabinet.
Refrigerant Leak Detector — A 4 to 20 mA / 0 to
5 vdc input is available on the CCM module [terminal J5-5 (–)
and J5-6 (+)] for a refrigerant leak detector. Enabling REFRIG-
ERANT LEAK OPTION (OPTIONS screen) will allow the PIC
III controls to go into an alarm state at a user configured level
(REFRIG LEAK ALARM mA). The input is configured for 4 to
20 mA by setting CCM DIP switch 1 on SW2 at the ON posi-
tion, or configured for 1 to 5 vdc by setting switch 1 at the OFF
position. The output of the refrigerant leak detector is displayed
as REFRIG LEAK SENSOR PPM on the MAINSTAT screen.
For a 1 to 5 vdc input, 1 vdc input represents 4 mA displayed
and 5 vdc input represents 20 mA displayed.
4 to 20 mA Kilowatt Output — An output is avail-
able on the CCM module [Terminal J8-1 (+) and J8-2 (–)] to
represent the power consumption of the chiller. The 4 to 20 mA
signal generated by the CCM module can be wired to the build-
ing automation or energy management system to monitor the
chiller’s energy consumption. A 4 mA signal represents the
chiller in an off state and a 20 mA signal represents the chiller
operating at its rated peak kilowatt consumption. The rated
peak kilowatt consumption is configured by the user in the
VFD_CONF display screen by the setting the RATED LINE
KILOWATTS from the Machine Electrical Data Nameplate.
The kilowatt output is designed for use with non-grounded
controllers with a maximum input impedance of 500 ohms.
Remote Reset of Alarms — A standard feature of the
PIC III controls is the ability to reset certain faults on a chiller
in a shutdown alarm state from a remote location. If the condi-
tion which caused the alarm has cleared the fault can be reset
and the chiller can be placed back into a normal CCN operating
mode when the REMOTE RESET OPTION (ICVC_PWD
menu) is set to ENABLE. A variety of Carrier Comfort Net-
work
®
software systems including ComfortVIEW™ or Net-
work Service Tool
®
can access the PIC III controls and reset
certain displayed alarms. Third party software from building
automation systems (BAS) or energy management systems
(EMS) can also access the PIC III controls through a Carrier
LEI (Local Equipment Interface) module and reset certain
faults that are displayed. All methods would access the
ICVC_PWD screen and force the RESET ALARM? point to
YES to reset the fault condition. If the PIC III controls have de-
termined that it is safe to start the chiller the CCN MODE?
point (ICVC_PWD screen) can be forced to YES to place the
chiller back into normal CCN operating mode. The only excep-
tions are the following alarms that cannot be reset from a re-
mote location: ALARM STATES #200, 201, 204, 206, 217,
218, 219, 220 and 236. To view alarm codes, refer to Trouble-
shooting Guide, Checking Display Messages, page 79. After
the alarm has been reset the PIC II control will increment the
Starts in 12 Hours counter by one upon restart. If the limit of 8
starts in a 12-hour period occurs Prestart Alert 100 must be
manually reset at the local chiller control panel (ICVC).
Condenser Pump Control — The chiller will moni-
tor the condenser pressure (CONDENSER PRESSURE) and
may turn on the condenser pump if the condenser pressure
becomes too high while the compressor is shut down. The
condenser pressure override (COND PRESS OVERRIDE)
parameter is used to determine this pressure point. COND
PRESS OVERRIDE is found in the SETUP1 display screen,
which is accessed from the EQUIPMENT SERVICE table.
The default value is 145 psig (543 kPa).
If the CONDENSER PRESSURE is greater than or equal to
the COND PRESS OVERRIDE, the condenser pump will ener-
gize to try to decrease the pressure and Alert 151 will be gener-
ated. The pump will turn off when the condenser pressure is
less than the COND PRESS OVERRIDE threshold.
Condenser Freeze Prevention — This control algo-
rithm helps prevent condenser tube freeze-up by energizing the
condenser pump relay through terminals 3 and 4 of the hazard-
ous voltage terminal strip (TB2) in the Control Center. The
PIC III controls the pump and, by starting it, helps to prevent
the liquid in the condenser from freezing. The PIC III can
perform this function whenever the chiller is not running ex-
cept when it is either actively in pumpdown or in pumpdown/
lockout with the freeze prevention disabled.
When the CONDENSER REFRIG TEMP is less than or
equal to the CONDENSER FREEZE POINT, the CONDENS-
ER LIQUID PUMP is energized until the CONDENSER
REFRIG TEMP is greater than the CONDENSER FREEZE
POINT plus 5º F (2.7º C) and the ENTERING CONDENSER
LIQUID TEMPERATURE is greater than or equal to the
CONDENSER FREEZE POINT. An alarm (244) is generated
if the chiller is in PUMPDOWN mode and the pump is ener-
gized. An alert (154) is generated if the chiller is not in PUMP-
DOWN mode and the pump is energized. If the chiller is in
RECYCLE SHUTDOWN mode, the mode will transition to a
non-recycle shutdown.
Tower Fan Relay Low and High — Low condenser
liquid temperature can cause the chiller to shut down if it
causes the condenser refrigerant temperature to be too low. The
tower fan relays, located on terminals 5-8 on the hazardous
voltage terminal strip (TB2) in the Control Center, are con-
trolled by the PIC III to energize and deenergize as the pressure
differential between cooler and condenser vessels changes.
This prevents excessively low condenser liquid temperatures.
The tower fan relay can only accomplish this if the relay has
been added to the cooling tower temperature controller.
The tower fan relay low is turned on whenever the condens-
er liquid pump is running, flow is verified, the difference
between cooler and condenser pressure is more than 30 psid
(207 kPad), and the ENTERING CONDENSER LIQUID
temperature is greater than 65 F (18.3 C).
The tower fan relay low is turned off when the CONDENS-
ER LIQUID PUMP is deenergized, when CONDENSER
LIQUID FLOW indication is lost, or under the following
conditions:
1. CALC EVAP SAT TEMP is less than EVAP SAT
OVERRIDE TEMP.
2. The difference between the CONDENSER PRESSURE
and EVAPORATOR PRESSURE is less than 25 psi
(172 kPa).
The tower fan relay high is turned on whenever the
condenser liquid pump is running, flow is verified and the
difference between cooler and condenser pressure is more than
35 psid (241.3 kPa) for ENTERING COND LIQUID tempera-
ture greater than the TOWER FAN HIGH SETPOINT
(SETPOINT menu, default 75 F [24 C]).
The tower fan relay high is turned off when the condenser
pump is off, flow is stopped, or the CALC EVAP SAT TEMP is
less than the EVAP SAT OVERRIDE TEMP and ENTERING
CONDENSER LIQUID is less than 70 F (21.1 C), The tower
fan relay high is also turned off when the difference between
CONDENSER PRESSURE and EVAPORATOR PRESSURE is
less than 28 Psid (193 kPa), and ENTERING CONDENSER
LIQUID temperature is less than TOWER FAN HIGH SET-
POINT minus 3 F (1.6 C).