SiUS121632EA
Control Specification
Functions and Control
83
Parameters
Q value
Indoor unit output determined from indoor unit volume, airflow rate and other factors.
S value: Indoor Unit Capacity
An S value is the capacity of the indoor unit, and is used for frequency command.
∆
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.
Values depend on the type of indoor unit.
∗
OFF = Thermostat OFF
Initial Frequency
When starting the compressor, or when conditions are varied due to a change of operating rooms,
the frequency must be initialized according to a total of the maximum
∆
D value of each room and a
total Q value (
Σ
Q) of the operating room (the room in which the thermostat is set to ON).
PI Control
1. P control
The
Σ∆
D value is calculated in each sampling time (20 seconds), and the frequency is adjusted
according to its difference from the frequency previously calculated.
2. I control
If the operating frequency does not change for more than a certain fixed time, the frequency is
adjusted according to the
Σ∆
D value.
When
Σ∆
D value is low, the frequency is lowered.
When
Σ∆
D value is high, the frequency is increased.
3. Limit of frequency increasing range
When the difference between the input current and the dropping value of the input current is
less than 1.5 A, the frequency increasing range must be limited.
4. Frequency control when other controls are functioning
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.
5. Upper and lower limit of frequency by PI control
The frequency upper and lower limits are set according to the total of S values. When the indoor
unit quiet operation commands come from more than one room or when the outdoor unit quiet
operation commands come from all the rooms, the upper limit frequency is lower than the usual
setting.
Ex:
Capacity
S value
Capacity
S value
9 kBtu/h
25
18 kBtu/h
50
12 kBtu/h
35
24 kBtu/h
60
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
Temperature
difference
∆
D
signal
–2.0°C (–3.6°F)
∗
OFF
0°C (0°F)
4
2.0°C (3.6°F)
8
4.0°C (7.2°F)
12
–1.5°C (–2.7°F)
1
0.5°C (0.9°F)
5
2.5°C (4.5°F)
9
4.5°C (8.1°F)
13
–1.0°C (–1.8°F)
2
1.0°C (1.8°F)
6
3.0°C (5.4°F)
10
5.0°C (9°F)
14
–0.5°C (–0.9°F)
3
1.5°C (2.7°F)
7
3.5°C (6.3°F)
11
5.5°C (9.9°F)
15
