Daikin AGZ030E, Инструкция по установке, эксплуатации и обслуживанию

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IOM 1206-7 • TRAILBLAZER
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MODEL AGZ CHILLERS 76 www.DaikinApplied.com
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UnCTIons
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.
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.
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
other than 0vdc (meaning the connected fans should run), but
any time both VFD’s are to be running the speed signals will
be the same (there is no independent speed control on the two
VFD’s within a circuit).
The speed will normally be controlled between the minimum
and maximum speed set points using a PID loop.
VFD State
The VFD speed signals should always be 0 when the fan stage
is 0.
When the condenser fan staging requires the fans connected
to a VFD to run, the VFD speed signal should be enabled and
control the speed as needed.
Stage Up Compensation
In order to create a smoother transition when another fan is
staged on, the VFD speed compensates by slowing down
initially. This is accomplished by adding the new fan stage up
deadband to the VFD target. The higher target causes the
VFD logic to decrease fan speed. Then, every 2 seconds,
0.1°C (0.18°F) is subtracted from the VFD target until it is
equal to the saturated condenser temperature target set point.
Sound Reduction Operation
When Sound Reduction is active, the maximum speed of
the VFD’s will be limited to the Sound Reduction fan speed
limit set point value. When Sound Reduction priority is set to
‘sound’, the fan speed limit is applied at all times regardless of
operating conditions.
When priority is set to ‘capacity’, the fan speed limit is in effect
unless saturated condenser temperature rises to a certain
value. That value is the high condenser pressure unload set
point converted to saturated temperature, less 5.56° (10°F).