Daikin F-Series Service Manual page 57

Control Specification
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
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
Frequency Initial Setting
〈 Outline 〉
When starting the compressor, or when conditions are varied due to the change of the room, the
frequency must be initialized according to the total of a maximum ∆ D value of the indoor unit
and the Q value of the indoor unit.
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
46
Set a minimum value as an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipes, freeze prevention, dew prevention,
fin thermistor temperature.
Set a maximum value as an lower limit frequency among the frequency lower limits of the
following functions:
Pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
∆D
Temperature Temperature
difference signal
∗Th
0
OFF
0.5 1
1.0 2
1.5 3
(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
difference signal difference
2.0 4
2.5 5
3.0 6
3.5 7
∆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
Si04-703A
∆D
signal
C
D
E
F