Daikin FTKS20CVMB(9) Service Manual page 61

Control Specification
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
Indoor Frequency Command (ΔD signal)
The difference between a room temperature and the temperature set by the remote control will
be taken as the "ΔD 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 ΔD 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 (Determine Frequency Up / Down by ΔD Signal)
1. P control
2. I control
3. Frequency management when other controls are functioning
4. Upper and lower limit of frequency by PI control
5. The frequency upper and lower limits are set depending on indoor unit.
52
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-up protection, 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.
ΔD
Temperature Temperature
difference signal
∗Th
0
OFF
0.5 1
1.0 2
1.5 3
Calculate ΔD 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 ΔD value, obtaining the fixed ΔD value.
When the ΔD value is small...lower the frequency.
When the ΔD value is large...increase the frequency.
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.
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.
ΔD
Temperature
difference signal difference
2.0 4
2.5 5
3.0 6
3.5 7
SiENBE04-512A
ΔD
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
ΔD
signal
C
D
E
F