Daikin FTX09NMVJU Service Manual page 53

SiUS091601E
When starting the compressor, the frequency is initialized according to the ∆D value of the indoor
Initial Frequency
unit.
∆D signal: Indoor frequency command
The difference between the room thermistor temperature and the target temperature is taken as the
∆D value and is used for ∆D signal of frequency command.
–2.0°C (–3.6°F) ∗OFF
–1.5°C (–2.7°F)
–1.0°C (–1.8°F)
–0.5°C (–0.9°F)
∗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
Functions and Control
∆D
Temperature Temperature
difference signal
1 0.5°C (0.9°F)
2 1.0°C (1.8°F)
3 1.5°C (2.7°F)
The ∆D value is calculated in each sampling time (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 lower than the usual setting.
∆D
Temperature
difference signal difference
0°C (0°F) 4 2.0°C (3.6°F)
5 2.5°C (4.5°F)
6 3.0°C (5.4°F)
7 3.5°C (6.3°F)
Control Specification
∆D
Temperature
signal difference signal
8 4.0°C (7.2°F)
9 4.5°C (8.1°F)
A 5.0°C (9.0°F)
B 5.5°C (9.9°F)
∆D
C
D
E
F
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