SiUS04-702 Control Specification (15/18/24 Class)
Function and Control 49
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 total of a maximum
∆
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
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