Daikin FTXZ25NV1B Service Manual page 60

Control Specification
When starting the compressor, the frequency is initialised according to the ∆D value of the
Initial Frequency
indoor unit.
<∆D signal: Indoor Frequency Command>
The difference between the room thermistor temperature and the target temperature is taken as
the ∆D signal and is used for frequency command
∗
OFF = Thermostat OFF
PI Control 1. P control
2. I control
3. Frequency control when other controls are functioning
4. Upper and lower limit of frequency by PI control
45
∆D
Temperature Temperature
difference signal
∗OFF
–2.0
–1.5 1
–1.0 2
–0.5 3
The ∆D value is calculated in each sampling time (15 ~ 20 seconds), and the frequency is
adjusted according to its difference from the frequency previously calculated.
If the operating frequency does not change for more than a certain fixed time, the frequency
is adjusted according to the ∆D value.
When the ∆D value is low, the frequency is lowered.
When the ∆D value is high, the frequency is increased.
When frequency is dropping;
Frequency control is carried out only when the frequency drops.
For limiting lower limit;
Frequency control is carried out only when the frequency rises.
The frequency upper and lower limits are set according to the command of the indoor unit.
When the indoor or outdoor unit quiet operation command comes from the indoor unit, the
upper limit frequency is lowered than the usual setting.
∆D
Temperature
difference signal difference
0 4
0.5 5
1.0 6
1.5 7
∆D
Temperature
signal difference
2.0 8 4.0
2.5 9 4.5
3.0 A 5.0
3.5 B 5.5
Function and Control
SiMT041311E
∆D
signal
C
D
E
F