94
AC-SVX001A-EN
Table 27. Diagnostics — main processor (continued)
Diagnostic
Name
Affects
Target
Severity
Persistence
Active
Modes
[Inactive
Modes]
Criteria
Reset
Level
Low
Evaporator
Rfgt Pressure -
Ckt2
Circuit Immediate Latch
Cprsr Prestart
and Cprsr
Energized
a. The Evap Refrig Pressure dropped below 10 Psia
just prior to compressor start (after EXV
preposition). b. During Early Startup Period: the
Evap Refrig Pressure fell below a pressure equal to
Condenser Pressure ÷ 8 but as limited to not less
than 6 or greater than 10 psia. c. After Early Startup
Period expires: The Evap Refrig Pressure fell below
16 Psia for 30 seconds or below 10 psia for 5
seconds. (Note: the Early Startup Period for RTAE it
is between 1 and 5 min as an inverse function of the
Cond Temp measured at time of circuit startup)
Local
Low
Evaporator
Rfgt
Temperature -
Ckt1
Circuit Immediate Latch
All Ckt Running
Modes [Service
Pumpdown]
The warmer of either the Evaporator Refrigerant Pool
Temperature or the Evaporator Saturated
Temperature for the respective circuit, dropped
below the Low Refrigerant Temperature Cutout
Setpoint for 2250F-sec (12F-sec/sec max rate
for early circuit startup period) while the circuit was
running. The minimum LERTC setpoint is -5F the
point at which oil separates from the refrigerant. The
integral is held nonvolatily though power down, is
continuously calculated, and can decay or build
during the circuit’s off cycle as conditions warrant
Remote
Low
Evaporator
Rfgt
Temperature -
Ckt2
Circuit Immediate Latch
All Ckt Running
Modes [Service
Pumpdown]
The warmer of either the Evaporator Refrigerant Pool
Temperature or the Evaporator Saturated
Temperature for the respective circuit, dropped
below the Low Refrigerant Temperature Cutout
Setpoint for 2250F-sec (12F-sec/sec max rate
for early circuit startup period) while the circuit was
running. The minimum LERTC setpoint is -5F the
point at which oil separates from the refrigerant. The
integral is held nonvolatily though power down, is
continuously calculated, and can decay or build
during the circuit’s off cycle as conditions warrant.
Remote
Low
Evaporator
Temp (Unit Off)
– Ckt1
Evap Pump
Info and
Special Action
NonLatch
Unit in Stop
Mode, or in
Auto Mode and
No Ckt's
Energzd [Any
Ckt Energzd]
The respective circuit’s “Chiller Off Cycle Freeze
Protection Integral” was seen to be higher than ½ of
its trip value while the chiller is in the Stop mode, or
in Auto mode with no compressors running, for one
minute and more. The COCFP integral is increased if
the Average of the Evap Water Temperature and the
Evap Refrigerant Pool Temp is below the value of the
Low Evap Rfgt Temp Cutout + 4°F. Energize Evap
Water Pump and Off-Cycle Freeze Avoidance Request
Relay until diagnostic auto resets, then return to
normal evap pump control and de-energize the
Freeze Avoidance Request. Automatic reset occurs
when the respective Evap Rfgt Pool Temp rises 2F
(1.1C) above the LERTC cutout setting and the
COCFP Integral is less than 1/3 of its trip value. This
diagnostic even while active, does not prevent
operation of either circuit. (At each circuit shutdown,
the COCFP integral is initialized to the LERTC
integral)
Remote
DDiiaaggnnoossttiiccss
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