23
(
Configuration
SERV
LOSP
) + 2.0° F (1.1º C) then re-
move a stage of capacity.
NOTE: The freeze set point is 34 F (1.1 C) for fresh water
systems (
Configuration
SERV
FLUD
=1
). The freeze set
point is Brine Freeze Set Point (
Configuration
SERV
LOSP
), for Medium Temperature Brine systems (
Configu-
ration
SERV
FLUD
=2
).
Override #2: Circuit A Low Saturated Suction Temperature
in Cooling
Override #3: Circuit B Low Saturated Suction Temperature
in Cooling
Override #4: Circuit C Low Saturated Suction Temperature
in Cooling — These overrides attempt to avoid the low suction
temperature alarms. This override is active only when more
than one compressor in a circuit is ON. If the Saturated Suction
Temperature is less than Brine Freeze Set Point (
Configura-
tion
SERV
LOSP
) –18.0 F (–10 C) for 90 seconds, or the
Saturated Suction Temperature is less than –4 F (–20 C), a
compressor in the affected circuit will be turned off.
Override #5: Low Temperature Cooling — This override re-
moves one stage of capacity when the difference between the
Control Point (
Run Status
VIEW
CTPT
) and the Leaving
Water Temperature (
Run Status
VIEW
LWT
) reaches a
predetermined limit and the rate of change of the water is 0 or
still decreasing.
Override #6: Low Temperature Cooling — This override re-
moves two stages of capacity when the Entering Water
Temperature (
Run Status
VIEW
EWT
) is less than the
Control Point (
Run Status
VIEW
CTPT
.)
Override #7: Ramp Loading — If the unit is configured for
ramp loading (
Configuration
OPTN
RL.S
=
ENBL
) and if
the difference between the Leaving Water Temperature and the
Control Point is greater than 4º F (2.2º C) and the rate of
change of the leaving water is greater than Cool Ramp Loading
Rate (
Setpoints
COOL
CRMP
) then no capacity stage
increase will be made. Operating mode 5 (MD05) will be in
effect.
Override #8: Service Manual Test Override — The manual
test consists in adding a stage of capacity every 30 seconds, un-
til the control enables all of the requested compressors and
Minimum Load Control selected in the
Comfort
Link™ display
Service Test menu. All safeties and higher priority overrides
are monitored and acted upon.
Override # 9: Demand Limit — This override mode is active
when a command to limit the capacity is received. If the
current unit capacity is greater than the active capacity limit
value, a stage is removed. If the current capacity is lower than
the capacity limit value, the control will not add a stage that
will result in the new capacity being greater then the capacity
limit value. Operating mode 4 (MD04) will be in effect.
Override #10: Cooler Interlock Override — This override
prohibits compressor operation until the Cooler Interlock
(
Inputs
GEN.I
LOCK
) is closed.
Override #11: High Temperature Cooling — This override
algorithm runs once when the unit is switched to ON. If the dif-
ference between the Leaving Water Temperature (
Run Status
VIEW
LWT
) and the Control Point (
Run Status
VIEW
CTPT
) exceeds a calculated value and the rate of
change of the water temperature is greater than –0.1º F/min, a
stage will be added.
Override #12: High Temperature Cooling — This override
runs only when Minimum Load Control is Enabled (
Configu-
ration
UNIT
HGBP
=
1
,
2
or
3
). This override will add a
stage of capacity if the next stage is Minimum Load Control,
when the difference between the Leaving Water Temperature
(
Run Status
VIEW
LWT
) and the Control Point (
Run
Status
VIEW
CTPT
) exceeds a calculated value and the
rate of change of the water temperature is greater than a fixed
value.
Override #13: Minimum On/Off and Off/On Time Delay —
Whenever a capacity step change has been made, either with
Minimum Load Control or a compressor, the control will re-
main at this capacity stage for the next 90 seconds. During this
time, no capacity control algorithm calculations will be made.
If the capacity step is a compressor, an additional 90-second
delay is added to the previous hold time (see Override #22).
This override allows the system to stabilize before another
capacity stage is added or removed. If a condition of a higher
priority override occurs, the higher priority override will take
precedence.
Override #14: Slow Change Override — This override pre-
vents compressor stage changes when the leaving temperature
is close to the control point and slowly moving towards the
control point.
Override #15: System Manager Capacity Control — If a
Chillervisor module is controlling the unit and the Chillervisor
module is controlling multiple chillers, the unit will add a stage
to attempt to load to the demand limited value.
Override #16: Circuit A High Pressure Override
Override #17: Circuit B High Pressure Override
Override #18: Circuit C High Pressure Override — This over-
ride attempts to avoid a high pressure failure. The algorithm is
run every 4 seconds. At least one compressor must be on in the
circuit. If the Saturated Condensing Temperature for the circuit
is above the High Pressure Threshold (
Configuration
SERV
HP.TH
) then a compressor for that circuit will
be removed. If Minimum Load Control was enabled for
High Ambient (
Configuration
UNIT
HGBP
=
3
), then the
Minimum Control Valve will be energized.
Override #19: Standby Mode — This override algorithm will
not allow a compressor to run if the unit is in Standby mode,
(
Run Status
VIEW
HC.ST
=
2
).
Override #22: Minimum On Time Delay — In addition to
Override #13 Minimum On/Off and Off/On Time Delay, for
compressor capacity changes, an
additional
90-second delay
will be added to Override #13 delay. No compressor will be
deenergized until 3 minutes have elapsed since the last com-
pressor has been turned ON. When this override is active, the
capacity control algorithm calculations will be performed, but
no capacity reduction will be made until the timer has expired.
A control with higher precedence will override the Minimum
On Time Delay.
Override #23: Circuit A Low Saturated Suction
Temperature in Cooling
Override #24: Circuit B Low Saturated Suction
Temperature in Cooling
Override #25: Circuit C Low Saturated Suction
Temperature in Cooling — If the circuit is operating in an
area close to the operational limit of the compressor, the circuit
capacity will remain at the same point or unload to raise the sat-
urated suction temperature. This algorithm will be active if at
least one compressor in the circuit is on and one of the follow-
ing conditions is true:
1. Saturated Suction Temperature is less than Brine Freeze
(
Configuration
SERV
LOSP
)
– 6º F (3.3º C).
2. Saturated Suction Temperature is less than Brine Freeze
(
Configuration
SERV
LOSP
) and the circuit ap-
proach (Leaving Water Temperature – Saturated Suction
Temperature) is greater than 15º F (8.3º C) and the Circuit
Superheat (Return Gas Temperature – Saturated Suction
Temperature) is greater than 15º F (8.3º C).
NOTE: The freeze set point is 34 F (1.1 C) for fresh
water systems (
Configuration
SERV
FLUD
=1
). The
freeze set point is Brine Freeze Set Point (
Configuration
SERV
LOSP
), for Medium Temperature Brine
systems (
Configuration
SERV
FLUD
=2
).
Содержание AQUASNAP 30RBA315
Страница 77: ...77 Fig 37 Control Schematic 30RB060 080 a30 4619...
Страница 78: ...78 Fig 38 Control Schematic 30RB090 150 a30 4620...
Страница 79: ...79 Fig 39 Control Schematic 30RB160 190 a30 4622...
Страница 80: ...80 Fig 40 Control Schematic 30RB210 300 a30 4622...
Страница 81: ...81 Fig 41 Heat Reclaim Control Schematic a30 4622...