Daikin Trailblazer AGZ030E-070E, Инструкция по установке, эксплуатации и обслуживанию

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Circuit Functions
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MODEL AGZ CHILLERS
Condenser Target
The condenser target is selected based on circuit capacity
using the condenser target set points. There are set points
that establish the condenser target for 33%, 50%, 67%, and
100% capacity. If the circuit has two compressors the set
points for 50% and 100% will be used. If the circuit has three
compressors then the set points for 33%, 67%, and 100% will
be used.
A minimum condenser target should be enforced. This
minimum will be calculated based on the evaporator LWT.
As the LWT varies from 7.2°C (45°F) to 32.2°C (90°F), the
minimum condenser target will vary from 23.9°C (75°F) to
48.9°C (120°F).
Staging Up
The first fan will not start until the evaporator pressure drop
or condenser pressure rise requirement for the No Pressure
Change After Start alarm is satisfied. Once that requirement
is met, if there is no fan VFD then the first condenser stage
should start when the saturated condenser temperature
exceeds the condenser target. If there is a fan VFD, then
the first stage should start when the saturated condenser
temperature exceeds the condenser target less 5.56°C (10°F).
After this, the four stage up dead band settings will be used:
Stage Up Deadband 1 – used when active condenser stage is 1
Stage Up Deadband 2 – used when active condenser stage is 2
Stage Up Deadband 3 – used when active condenser stage is 3
Stage Up Deadband 4 – used when active condenser stage is 4, 5,
or 6
When the saturated condenser temperature is above the target
plus the active deadband, stage up error is
accumulated.
Stage Up Error Step = Saturated Condenser Temperature –
( Stage Up dead band)
The Stage Up Error Step is added to Stage Up Accumulator
once every 5 seconds, only if the Saturated Condenser
Refrigerant Temperature is not falling. When Stage Up Error
Accumulator is greater than 11°C (19.8°F) another stage is
added.
When a stage up occurs or the saturated condenser
temperature falls back within the stage up dead band the Stage
Up Accumulator is reset to zero.
For units configured with microchannel condenser coils, there
are additional conditions which may cause the fan stage to
increase:
• If circuit has two compressors, the second compressor
on a circuit starts, the circuit is not already at the
maximum condenser stage, and the condenser saturated
temperature is higher than 37.78°C (100°F), then a
condenser stage will be added immediately.
• If the condenser stage is not already at the maximum,
the saturated condenser temperature exceeds 56.67°C
(134°F), it has been at least 5 seconds since adding
a condenser stage, and the saturated condenser
temperature is not dropping, then a condenser stage will
be added immediately.
In addition, if the circuit has 4 fans, or it has 6 fans and no
fan VFD’s, then the first condenser stage may be skipped at
startup. This happens if the OAT is at least 21.11°C (70°F)
when the first condenser stage would normally be started, in
which case it will go directly to the second stage.
If the circuit has two fan VFDs and OAT is at least 10°C (50°F)
when the first condenser stage would normally be started.
Both of these evaluation points are in place to address
potential spikes in condenser pressure resulting from the lower
volume of the microchannel coils.
Staging Down
Four stage down dead bands shall be used.
Stage Down Deadband 1 – used when active condenser stage is 1
Stage Down Deadband 2 – used when active condenser stage is 2
Stage Down Deadband 3 – used when active condenser stage is 3
Stage Down Deadband 4 – used when active condenser stage is 4,
5, or 6
When the saturated condenser refrigerant temperature is
below the target – the active deadband, a stage down error is
accumulated.
Stage Down Error Step = (Target - Stage Down dead band)
- Saturated Condenser Temperature
The Stage Down Error Step is added to Stage Down
Accumulator once every 5 seconds. When the Stage Down
Error Accumulator is greater than 2.8°C (5°F) another stage of
condenser fans is removed.
When a stage down occurs or the saturated temperature rises
back above the target minus the Stage Down dead band, the
Stage Down Error Accumulator is reset to zero.
Limiting Last Stage
For AGZE models with either 5 or 7 fans per circuit and two fan
VFD’s per circuit, the last fan stage on those configurations is
a fixed speed fan. The last fan stage will be turned off and will
not be allowed to activate when noise reduction is active.
The last fan stage will also be turned off if OAT is less than
23.89°C (75°F) and it will not be allowed to activate if OAT is
less than 25.56°C (78°F).
VFD Control
Configurations can include a VFD on the first fan on the circuit,
or two VFD’s on the circuit with either all fans connected to
those VFD’s or all except one (leaving one fixed speed fan).
The VFD’s will vary fan speed to drive the saturated condenser
temperature to a target value. The target value is normally the
same as the saturated condenser temperature target.
Note that when there are two VFD’s per circuit, there are
two separate speed signals on each circuit. Staging logic will
determine when each speed signal output should be something