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When a capacity increase occurs, a time delay starts; and
when a capacity decrease occurs, a separate time delay starts.
While either of these delays is active, no normal capacity
changes will occur. The load and unload delay times are
calculated values.
Circuit State = Pumpdown - Speed command will drop 2 Hz
every second until reaching the minimum for the configuration.
Manual Speed Control
The speed of the compressor may be controlled manually.
Manual speed control is enabled via a set point with choices
of Auto or Manual. Another set point allows setting the
compressor speed. However, the resulting compressor speed
is still limited to the range from the minimum speed based on
configuration up to the Compressor Maximum Speed set point.
The compressor speed will be stepped up or down until it is
equal to the speed that corresponds to the manual speed set
point. Changes to the speed will be made as fast as allowed by
the calculated load and unload delays. Speed control may be
set to Manual only when circuit state is Start or Run.
Capacity control shall revert back to automatic control if either:
• the circuit state changes from Start or Run to another
state
• capacity control has been set to Manual for four hours
Load and Unload Delay
LWT Error determines the delays for load and unload
commands.
Table 48: Load and Unload Delay Conditions
LWT Error
LWT Error > Startup Delta
T set point
0.1°C ≤ LWT Error ≤
Startup Delta T set point
– (Stage Down Delta T
set point) ≤ LWT Error ≤
-0.1°C
LWT Error < -(Stage Down
Delta T set point)
VR Solenoid Valve Control
There are three solenoid valves for changing volume ratio of
the compressor:
• 50 VR solenoid valve
• 75 VR solenoid valve
• 100 VR solenoid valve
The compressor should start with all three solenoid valves off.
After compressor has been running for at least 20 seconds, the
control logic will "stage" the solenoid valves.
which VR solenoid valves are on at each stage as well as
stage up and stage down conditions. These staging conditions
must be active for 30 seconds to trigger each stage up or
down.
www.DaikinApplied.com
Delay
Load command delay is 5
seconds
Load command delay will vary
from 5 seconds to 10 seconds
Unload command delay will
vary from 3 seconds to 6
seconds
Unload command delay is 3
seconds
Table 49
shows
Table 49: VR Solenoid Valve Control Stages
50
Stage
VR
VR
SV
0
1.6
Off
1
1.8
On
2
2.4
Off
3
3.1
On
When the circuit state becomes Pumpdown or Off, all VR
solenoids should be turned off.
Condenser Fan Control
Condenser fan control will vary in operation based on the Fan
VFD Configuration set point.
Table 50: Condenser Fan Control Configurations
Fan VFD
Control Type
Configuration
None
Staging only
1st Fan VFD
Staging and speed
control of 1st fan on
the circuit
All Fan VFD
Staging and speed
control of all fans
Physical Fan Layout
Fans are numbered as shown below (top view of chiller). Fan
numbers start on the left side of the circuit, closest to the
control box when facing the control box.
Circuit #1 fans start at 101 and can run through 116 depending
on the number of fans on the circuit. Circuit #2 fans start at 201
and can run through 214 depending on the number of fans on
the circuit.
Figure 63: Fan Numbering Diagram - Representative
Circuit 1
Control
101
103
105
107
Box
End
102
104
106
108
NOTE: Number of fans vary by unit configuration
61
IOM 1242-2 • PATHFINDER
C
IrCuIT
75
100
Stage Up
VR
VR
Condition
SV
SV
Pressure
Off
Off
Ratio > 2.10
Pressure
Off
Off
Ratio > 2.85
Pressure
On
Off
Ratio > 3.85
On
On
n/a
Control
Mechanism
Contactors
Contactors and
VFD
Integrated VFD on
each motor
Circuit 2
109
111
113
115
201
203
205
207
110
112
114
116
202
204
206
208
MODEL AWV CHILLERS
®
f
unCTIons
Stage Down
Condition
n/a
Pressure
Ratio < 1.90
Pressure
Ratio < 2.65
Pressure
Ratio < 3.65
209
211
213
210
212
214
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