Carrier AQUASNAP MPW015-045 Operation And Service Manual page 50

ALARM/ ALARM
ALERT OR DESCRIPTION
CODE ALERT
Strainer Blowdown
T302 Alert Scheduled
Maintenance Due
Current Sensor Board
T500 Alert
A1 Failure
Current Sensor Board
T501 Alert
A2 Failure
Current Sensor Board
T502 Alert
A3 Failure
T950 Alert Loss of Communication
with Water System
Manager
T951 Alert Loss of Communication
with Chillervisor System
Manager
LEGEND
CCN — Carrier Comfort Network
CSB — Current Sensor Board
CSM — Chiller System Manager
CXB — Compressor Expansion Board
EEPROM — Electronic Eraseable Programmable Read Only Memory
EMM — Energy Management Module
EWT — Entering Fluid Temperature
EXV — Electronic Expansion Valve
HSM — Hydronic System Manager
LCW — Leaving Chilled Water
LWT — Leaving Fluid Temperature
MBB — Main Base Board
OAT — Outdoor-Air Temperature
RGT — Return Gas Thermistor
WSM — Water System Manager
COMPRESSOR FAILURE ALERTS
A048 (Circuit A Compressor Availability Alarm) — This
alarm occurs when two compressors are unavailable to run on
a 3 compressor circuit. The control ensures proper oil return by
ensuring a circuit does not operate with one compressor for
longer than one hour of cumulative run time.
T051, T052, T053 (Circuit A Compresser Failures) — Alert
codes 051, 052, and 053 are for compressors A1, A2, and A3
respectively. These alerts occur when the current sensor (CS)
does not detect compressor current during compressor opera-
tion. When this occurs, the control turns off the compressor.
If the current sensor board reads OFF while the compressor
relay has been commanded ON, an alert is generated.
POSSIBLE CAUSES
Compressor Overload — Either the compressor internal over-
load protector is open or the external overload protector (Kri-
wan module) has activated. The external overload protector
modules are mounted in the compressor wiring junction box.
Temperature sensors embedded in the compressor motor wind-
ings are the inputs to the module. The module is powered with
24 vac from the units main control box. The module output is a
normally closed contact that is wired in series with the com-
pressor contactor coil. In a compressor motor overload condi-
tion, contact opens, deenergizing the compressor contactor.
Low Refrigerant Charge — If the compressor operates for an
extended period of time with low refrigerant charge, the com-
pressor ASTP device will open, which will cause the compres-
sor to trip on its overload protection device.
Circuit Breaker Trip — The compressors are protected from
short circuit by a breaker in the control box.
Wiring Error — A wiring error might not allow the compres-
sor to start.
Table 38 — Alarm and Alert Codes (cont)
WHY WAS THIS
ALARM
GENERATED?
Strainer Service
Countdown (S.T.DN)
expired. Complete strainer
blowdown and enter 'YES'
for Strainer Maintenance
Done (S.T.MN) item.
Alert occurs when CSB out-
put is a constant high value
Alert occurs when CSB out-
put is a constant high value
Alert occurs when CSB out-
put is a constant high value
No communications have
been received by the MBB
within 5 minutes of last
transmission
No communications have
been received by the MBB
within 5 minutes of last
transmission
50
ACTION TAKEN
BY CONTROL METHOD
None Automatic
Compressor A1 shut
Automatic
down
Compressor A2 shut
Automatic
down
Compressor A3 shut
Automatic
down
WSM forces removed. Automatic
Chiller runs under own
control
CSM forces removed. Automatic
Chiller runs under own
control
To check out alerts T051-T053:
1. Turn on the compressor in question using Service Test
mode. If the compressor does not start, then most likely
the problem is one of the following: HPS open, open in-
ternal protection, circuit breaker trip, incorrect safety wir-
ing, or incorrect compressor wiring.
2. If the compressor does start, verify it is rotating in the cor-
rect direction.
IMPORTANT: Prolonged operation in the wrong direction
can damage the compressor. Correct rotation can be veri-
fied by a gage set and looking for a differential pressure
rise on start-up.
IMPORTANT: If the CS is always detecting current, verify
that the compressor is on. If the compressor is on, check
the contactor and the relay on the MBB. If the compressor
is off and there is no current, verify the CSB wiring and
replace if necessary.
IMPORTANT: Return to Normal mode and observe com-
pressor operation to verify that compressor current sensor
is working.
COMPRESSOR STUCK ON FAILURE ALARMS
Circuit A A051, A052, A053 — Alarm codes 051, 052, and
053 are for compressors A1, A2, and A3. These alarms occur
when the CSB detects current when the compressor should be
off. When this occurs, the control turns off the compressor.
If the current sensor board reads ON while the compressor
relay has been commanded OFF for a period of 4 continuous
seconds, an alarm is generated. These alarms are only moni-
tored for a period of 10 seconds after the compressor relay has
RESET PROBABLE
CAUSE
Routine strainer
maintenance
required
CSB failure.
CSB failure.
CSB failure.
Failed module, wiring
error, failed
transformer, loose
connection plug,
wrong address
Failed module, wiring
error, failed
transformer, loose
connection plug,
wrong address