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Criteria for Mode — Tested when the unit is ON. This mode
is active when Ice Setpoint (Setpoints
in use. While in this mode, the Active Setpoint (Run Status
VIEW
SETP) will show the CSP.3 value.
Action Taken — The unit will operate to the Ice Setpoint
(CSP.3).
Termination — This mode will terminate when the Ice Set-
point (CSP.3) is no longer in use.
Possible Causes — This mode is in effect only due to pro-
gramming options.
MODE 19 Operating Mode
Active on Cir A
MODE 20 (Operating Mode
Active on Cir B
Criteria for Mode — This mode is not supported for Cooling
Only units.
Action Taken — None.
Termination — None.
Possible Causes — This mode is in effect only due to pro-
gramming options.
MODE 21 (Operating Mode
Suction Circuit A
MODE 22 (Operating Mode
Suction Circuit B
MODE 23 (Operating Mode
Suction Circuit C
Criteria for Mode — The criteria are tested when the circuit is
ON. The appropriate circuit mode will be active if one of the
following conditions is true:
1. If the circuit's Saturated Suction Temperature (SST) is
more than 6° F (3.3° C) less than the freeze point and
both the cooler approach (Leaving Water Temperature-
SST) and superheat (Suction Gas Temperature – SST) are
greater than 15° F (8.3° C).
2. If there is more than 1 compressor ON in the circuit and
the circuit's SST is greater than 18° F (10.0° C) below the
freeze point for more than 90 seconds.
3. If there is more than 1 compressor ON in the circuit and
the circuit's SST is greater than –4° F (–20.0° C) and the
SST 30 seconds ago was 18° F (10.0° C) below the freeze
point.
4. If the circuit's saturated suction temperature is greater
than 6° F (3.3° C) below the freeze point for more than
3 minutes.
For a fresh water system (Configuration
=1), the freeze point is 34° F (1.1° C). For medium temperature
brine systems, (Configuration
point is Brine Freeze Set Point (Configuration
LOSP).
Action Taken — For criterion 1, no additional stages will be
added. For criteria 2, 3 and 4, one stage of capacity will be
removed.
Termination — The mode will terminate when the circuit's
Saturated Suction Temperature is greater than the freeze point
minus 6° F (3.3° C) or the circuit has alarmed.
Possible Causes — If this condition is encountered, see Possi-
ble Causes for Alarms P.05, P.06, and P.07 on page 67.
MODE 24 (Operating Mode
DGT Circuit A
MODE 25 (Operating Mode
DGT Circuit B
MODE 26 (Operating Mode
DGT Circuit C
COOL
CSP.3) is
MODE
MD19) — Defrost
MODE
MD20) — Defrost
MODE
MD21) —
MODE
MD22) —
MODE
MD23) —
SERV
FLUD
SERV
FLUD=2), the freeze
SERV
MODE
MD24) —
MODE
MD25) —
MODE
MD26) —
Criteria for Mode — This mode is tested for when any circuit
is running. The circuit saturated condensing and suction tem-
peratures are monitored to ensure that the compressors always
operate withing their allowed "map." Operation at conditions
at or outside the "map" boundaries will cause this mode to be
in effect. Operation at extremely low suction pressures and
high condensing temperatures will cause the mode to be
generated.
Action Taken — The circuit will not be allowed to increase ca-
pacity and may be automatically unloaded or stopped.
Termination — This mode will terminate when or if the circuit
refrigerant conditions return to within the compressor "map."
Possible Causes — This mode could be in effect due to a low
fluid flow rate, overcharge of oil in a circuit, dirty condenser
coils, refrigerant overcharge, or excessive brine concentration.
MODE 27 (Operating Mode
Pres Override Cir A
MODE 28 (Operating Mode
Pres Override Cir B
MODE 29 (Operating Mode
Pres Override Cir C
Low
Criteria for Mode — Tested when the circuit is ON. The
appropriate circuit mode will be active if the discharge pressure
for the circuit, Discharge Pressure Circuit A (Pressure
Low
PRC.A
DP.A), Discharge Pressure Circuit B (Pres-
sure
PRC.B
Low
(Pressure
PRC.C
Threshold (Configuration
Action Taken — The capacity of the affected circuit will be
reduced. If the unit is equipped with Minimum Load Control
and has been configured for High Ambient (Configuration
UNIT
HGBP=3), the minimum load control valve will be
energized. Two minutes following the capacity reduction, the
circuit's saturated condensing temperature (SCT) is calculated
and stored. The affected circuit will not be allowed to add ca-
pacity for at least 5 minutes following the capacity reduction. If
after 5 minutes, the circuit's saturated condensing temperature
is less than SCT – 3° F (1.7° C), if required, another stage of
capacity will be added.
If additional steps of capacity are required, the control will
look for other circuits to add capacity.
Termination — This mode will terminate once the circuit's
saturated condensing temperature is less than SCT – 3° F
(1.7° C).
Possible Causes — If this condition is encountered, see Possi-
ble Causes for Alarm A1.03. on page 64.
MODE 30 (Operating Mode
Superheat Circuit A
MODE 31 (Operating Mode
Superheat Circuit B
MODE 32 (Operating Mode
Superheat Circuit C
Criteria for Mode — Tested when the circuit is ON with at
least 1 compressor ON. The appropriate circuit mode will be
active is the circuit's superheat is less than 5° F (2.8° C).
Action Taken — No additional stages of circuit capacity will
be added until the circuit's superheat is greater than 5° F
(2.8° C).
The control will look for other circuits to add capacity if
High
additional steps of capacity are required.
Termination — This mode will terminate once the affected
High
circuit's superheat is greater than 5° F (2.8° C).
Possible Causes — If this condition is encountered, see Possi-
High
ble Causes for Alarms P.11, P.12 and P.13 on page 67.
48
MODE
MODE
MODE
DP.B), or Discharge Pressure Circuit C
DP.C) is greater than the High Pressure
SERV
HP.TH).
MODE
MODE
MODE
MD27) —
High
MD28) —
High
MD29) —
High
MD30) —
Low
MD31) —
Low
MD32) —
Low
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