Daikin ARK25BVMB, Service Manual

Page: 56 / 201

SiBE04-302 Control Specification
Function and Control 47
3. Determine lower limit frequency
„
Set a maximum value as an lower limit frequency among the frequency lower limits of the
following functions:
Pressure difference upkeep.
4. Determine prohibited frequency
„
There is a certain prohibited frequency such as a power supply 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
∆
D 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
∆
D Signal)
1. P control
Calculate
∆
D value in each sampling time (20 seconds), and adjust the frequency according
to its difference from the frequency previously calculated.
2. I control
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.
3. Limit of frequency variation width
When the difference between input current and input current drooping value is less than 1.5
A, the frequency increase width must be limited.
4. Frequency management when other controls are functioning
„
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.
5. Upper and lower limit of frequency by PI control
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.
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
0
∗
Th
OFF
2.0 4 4.0 8 6.0 C
0.5 1 2.5 5 4.5 9 6.5 D
1.0 2 3.0 6 5.0 A 7.0 E
1.5 3 3.5 7 5.5 B 7.5 F