Safety Devices; Compressor Protection; Oil Separator Heaters (30Gx); Cooler Protection - Carrier ComfortLink 6 Series Controls, Start-Up, Operation, Service, And Troubleshooting

Safety Devices —
The 30GX,HX chillers contain many
safety devices and protection logic built into the electronic
control. Following is a description of the major safeties.

COMPRESSOR PROTECTION

Motor Overload — The compressor protection modules
(CCP) protect each compressor against overcurrent. Do not
bypass the current transducers or make any changes to the
factory-installed and configured 8-pin headers. The configura-
tion of these headers defines the Must Trip Amps (MTA) at
which the CCP will turn the compressors off. Determine the
cause for trouble and correct the problem before resetting the
CCP. See Appendix A for setting of MTAs and configuration
headers.
Each CCP board also reads the status of each compressor's
high-pressure switch. All compressors have factory-installed
high-pressure switches. See Table 41.
Table 41 — High-pressure Switch Settings
SWITCH SETTING
UNIT
psig
30GX 303 ±7
30HXA 275 ±7
30HXC 191 ±7
If the switch opens during operation, the compressor will be
shut down. The CCP will reset automatically when the switch
closes, however, a manual reset is required to restart the
compressor.
OIL SEPARATOR HEATERS (30GX) — Each oil separator
circuit has a heater mounted on the underside of the vessel.
The heater is energized with control circuit power. Oil heaters
are energized when the discharge gas temperature falls below
105 F (40.6 C). The heaters are deenergized when the
discharge gas temperature rises above 110 F (43.3 C). The con-
trol will allow the chiller to attempt to start with the heaters
energized and will keep the heaters on, even when running,
until the discharge gas temperature reaches 110 F (43.3 C).
Note that the oil heaters are deenergized if the oil level switch
is open.

COOLER PROTECTION

Low Water Temperature — Microprocessor is programmed
to shut the chiller down if the leaving fluid temperature drops
below 34 F (1.1 C) for water or more than 8° F (4.4° C) below
set point for brine units. When the fluid temperature rises 6° F
(3.3° C) above the leaving fluid set point, the safety resets and
the chiller restarts. Reset is automatic as long as this is the first
occurrence of the day.
IMPORTANT: If the unit is installed in an area where
ambient temperatures fall below 32 F (0° C), cooler
heaters and inhibited ethylene glycol or other suitable
solution must be used in the chilled fluid circuit.
Relief Devices —
Fusible plugs are located in each cir-
cuit (30GXN,R only) between the condenser and the liquid
line shutoff valve.
PRESSURE RELIEF VALVES — Valves are installed in each
circuit and are located on all coolers. One relief valve is also
installed on each 30HXC condenser. Both circuits' oil separa-
tors on 30GXN,R and 30HXA units have factory-installed
relief valves as well. These valves are designed to relieve if an
abnormal pressure condition arises. Relief valves on all coolers
and 30HXC condensers relieve at 220 psi (1517 kPa). Relief
valves on 30GXN,R and 30HXA oil separators relieve at
320 psi (2206 kPa). All 30HXA, HXC units with factory-
installed suction service valves also have a relief valve in each
compressor discharge line. These valves are designed to
relieve at 350 psig (2413 kPa). These valves should not be
capped. If a valve relieves, it should be replaced. If the valve is
kPa
2089 ±48
1896 ±48
1317 ±48
68
not replaced, it may relieve at a lower pressure, or leak due to
trapped dirt from the system which may prevent resealing.
Pressure relief valves located on cooler and condenser shells
and 30HXA oil separator shells have
for relief. The 30GXN,R oil separators have
connections. Some local building codes require that relieved
gases be removed. This connection allows conformance to this
requirement.

Control Modules

Turn controller power off before servicing controls. This
ensures safety and prevents damage to controller.

MAIN BASE BOARD (MBB), SCREW COMPRESSOR

BOARD (SCB), EXPANSION
(EXV), ENERGY MANAGEMENT MODULE (EMM),
COMFORTLINK™ COMPRESSOR
BOARDS (CCP) AND THE NAVIGATOR — All of the
ComfortLink modules perform continuous diagnostic evalua-
tions of the condition of the hardware. Proper operation and
communication of these modules is indicated by LEDs on the
surface of each module (all except the Navigator that displays
'Communication Failure' when it occurs).
RED LED — All module red LEDs will blink in unison at a
1 to 2 second rate when communicating and functioning
properly. Lighted continuously indicates a problem requiring
replacement of module. Off continuously indicates power
should be checked. If there is no input power, check fuses. If
fuse is bad, check for shorted secondary of transformer, tripped
circuit breaker or bad module. An LED blinking at a rate of
twice per second indicates potential loss of program. The
suspect board(s) should be downloaded using the SmartLoader
program. If this is not successful, the module should be
replaced.
GREEN LED — Each module has a green LED that should
always be blinking when power is on. Each module's green
LED will be blinking at different rates. This is a normal condi-
tion. If the green LED is not blinking, check the red LED. If the
red LED is normal, verify that all communication connections
(J3 for MBB, J3/J4 for SCB, EXV, EMM and J10/J11 for
CCP1 and CCP2) are correct. If wiring is correct, check the
Main Base Board instance jumper (should be set to '1'). The
EXV, EMM and SCB module address switches should all be
set to ON. For CCP1, switch 1 should be On and switches 2, 3
and 4 should be Off. For CCP2, switches 1,3 and 4 should be
On and switch 2 should be Off. Remote terminal strip (TB3)
connections are made to the Main Base Board at plug MBB-J5.
YELLOW LED — The Main Base Board (MBB) has a yel-
low LED. This light will blink whenever CCN (Carrier
Comfort Network) communications are in progress. Only the
MBB is designed to communication on the CCN bus. All
other modules (including the Navigator) are designed to
communicate only on the LEN bus.
The majority of the system operating intelligence resides in
the MBB, however each individual module does have its own
operating software. The machine operator communicates with
the MBB through the Navigator. Communications between all
modules is accomplished by a 3-wire sensor bus called
the Local Equipment Network (LEN). These 3 wires run in
parallel from module to module.
For all models, control modules are powered by 24 vac
power sources protected by circuit breakers. Separate power
sources are used for the CCP modules. Refer to the 24-v wiring
schematic located on the chiller for detailed information. Refer
to Table 42 for control troubleshooting information.
3
/ -in. NPT connections
4
1
/ -in. male flare
2
VALVE BOARD
PROTECTION