Daikin CTXU25G2V1B Service Manual page 33

Control Specification
Indoor Frequency Command ( ∆ D signal)
The difference between a room temperature and the temperature set by the remote controller
will be taken as the " ∆ D signal" and is used for frequency command.
∗
Th OFF = Thermostat OFF
Indoor Unit Capacity (S value)
The capacity of the indoor unit is a "S" value and is used for frequency command.
ex.)
Frequency Initial Setting
< Outline >
When starting the compressor, or when conditions are varied due to the change of the operating
room, the frequency must be initialized according to the total of a maximum ∆ D value of each
room and a total value of Q ( Σ Q) of the operating room (the room in which the thermostat is set
to ON).
Q value: Indoor unit output determined from indoor unit volume, airflow rate and other factors.
PI Control
1. P control
2. I control
3. Limit of frequency variation width
4. Frequency management when other controls are functioning
5. Upper and lower limit of frequency by PI control
30
∆D
Temperature Temperature
difference signal
∗Th
0
OFF
0.5 1
1.0 2
1.5 3
Capacity
2.5 kW
3.5 kW
(Determine Frequency Up/Down by ∆ D Signal)
Calculate a total of the ∆ D value in each sampling time (20 seconds), and adjust the
frequency according to its difference from the frequency previously calculated.
If the operating frequency is not change more than a certain fixed time, adjust the frequency
up and down according to the Σ∆ D value, obtaining the fixed Σ∆ D value.
When the Σ∆ D value is small...lower the frequency.
When the Σ∆ D value is large...increase the frequency.
When the difference between input current and input current drooping value is less than 1 A,
the frequency increase width must be limited.
When each frequency is drooping;
Frequency management is carried out only when the frequency droops.
For limiting lower limit
Frequency management is carried out only when the frequency rises.
The frequency upper and lower limits are set depending on the total of S values of operating
room. When low noise commands come from the indoor unit more than one room or when
outdoor unit low noise or quiet commands come from all the rooms, the upper limit frequency
must be lowered than the usual setting.
∆D
Temperature
difference signal difference
2.0 4
2.5 5
3.0 6
3.5 7
S value
25
35
∆D
Temperature
signal difference
4.0 8 6.0
4.5 9 6.5
5.0 A 7.0
5.5 B 7.5
Function and Control
SiBE12-908
∆D
signal
C
D
E
F