Installation and Maintenance Manual

Diagnostics
RTAE-SVX001B-EN 81
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 2250F-sec (12F-sec/sec
max rate for early circuit startup period) while the circuit was
running. The minimum LERTC setpoint is -5F 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 2250°F-sec (12°F-sec/sec
max rate for early circuit startup period) while the circuit was
running. The minimum LERTC setpoint is -5°F 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 2°F (1.1°C) 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
Low Evaporator
Temp (Unit Off)
– Ckt2
Evap Pump
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
Temperatures 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 2°F (1.1°C) 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
Table 33. Main processor diagnostics (continued)
Diagnostic
Name
Affects
Target Severity Persistence
Active Modes
[Inactive
Modes] Criteria
Reset
Level