Daikin FTKN09NMVJU Service Manual page 47

SiUS041501E
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
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 recognized
as the ∆D signal and is used for 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
Function and Control
The minimum value is set as an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipe temperature, heating peak-cut, freeze-up
protection, defrost control.
The maximum value is set as an lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
∆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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