Daikin FT25CV1A Service Manual page 52

Si01-406
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.
∗
Frequency Initial Setting
When starting the compressor, or when conditions are varied due to the change of the room, the
frequency must be initialized according to the ∆ D value of the indoor unit and the Q value of the
indoor unit.
Q value: Indoor unit output determined from indoor unit volume, air flow 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
Functions and Control
∆D
Temperature
difference signal
∗Th
0
OFF
0.5 1
1.0 2
1.5 3
Th OFF = Thermostat OFF
Outline
(Determine Frequency Up / Down by ∆ D Signal)
Calculate ∆ 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 ∆ D value, obtaining the fixed ∆ D value.
When the ∆ D value is small...lower the frequency.
When the ∆ D value is large...increase the frequency.
When the difference between input current and input current drooping value is less than 1.5
A, the frequency increase width must be limited.
When 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 indoor unit.
When low noise commands come from the indoor unit or when outdoor unit low noise or
quiet commands come from indoor unit, the upper limit frequency must be lowered than the
usual setting.
∆D
Temperature Temperature
difference signal
2.0 4
2.5 5
3.0 6
3.5 7
Control for Heat Pump Models
∆D
Temperature
difference signal difference
4.0 8
4.5 9
5.0 A
5.5 B
∆D
signal
6.0 C
6.5 D
7.0 E
7.5 F
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