Control Specification SiENBE12-713
84 Function and Control
2. Determine upper limit frequency
$ Set a minimum value as an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipes, freeze-up protection, dew prevention,
fin thermistor temperature.
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 (ΔD signal)
The difference between a room temperature and the temperature set by the remote control will
be taken as the “ΔD signal” and is used for frequency command.
∗Th OFF = Thermostat OFF
Indoor Unit Capacity (S value)
The capacity of the indoor unit is a “S” value and is used for frequency command.
Frequency Initial Setting
<Outline>
When starting the compressor, or when conditions are varied due to the change of the operating
room, the frequency must be initialized according to the total of a maximum ΔD value of each room
and a total value of Q (ΣQ) of the operating room (the room in which the thermostat is set to ON).
Q value: Indoor unit output determined from indoor unit volume, air flow rate and other factors.
PI Control (Determine Frequency Up / Down by ΔD Signal)
1. P control
Calculate a total of the ΔD 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 ΣΔD value, obtaining the fixed ΣΔD value.
When the ΣΔD value is small...lower the frequency.
When the ΣΔD 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 each 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.
Temperature
difference
ΔD
signal
Temperature
difference
ΔD
signal
Temperature
difference
ΔD
signal
Temperature
difference
ΔD
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
Capacity S value Capacity S value
2.5 kW 25 6.0 kW 60
3.5 kW 35 7.1 kW 71
5.0 kW 50
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