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2WAY SYSTEM
Control Functions - Outdoor unit
1
3. Compressor Control
2WAY VRF SYSTEM
Control Functions
3. Compressor Control
The compressor with higher priority order starts according to the priority orders described on previous page.
The compressor with lower priority order stops according to the priority orders described on previous page.
The inverter compressor can operate within the range in the table below.
2. Operating compressors
When the high pressure is over 2.8MPa, the upper limit frequency is restricted.
The frequency range in the table above is subject to change without notice.
*
*1 The minimum Hz changes according to the outdoor air temperature during cooling operation.
*2
・
The upper limit frequency is sometimes restricted to 50Hz until the compressor gets warmer.
・
During the oil recovery control among the systems or 4-way valve control, the upper limit frequency is 65Hz.
・
When operation started under the temperature of
10°C
＜
outdoor air temperature ≤ 48°C, the
minimum Hz becomes 15Hz.
3. Stopping compressors
(3) Operation When Starting 2 Compressors Mounted in Outdoor Unit
(4) Operating Frequency Range of Inverter Compressor
Once a compressor stops, it will not start for a period of 3 minutes (3-minute forced OFF).
However, this does not apply when the compressor was forced to stop as the result of a special control operation.
(start control, defrost control, refrigerant oil recovery control, etc.)
(5) Forced Stopping of Compressor
(6) Horsepower Control (Roadmap Control)
When necessary capacity gradually increases and one more inverter compressor is additionally started under
the present operating compressor, reduce the compressor frequency to 25Hz temporarily and then start an
additional compressor.
The operation noted above is performed when the inverter compressor 1 or 2 is additionally started.
If necessary capacity is initially higher and two compressors are started simultaneously, the operation noted
above is not performed and both of them are regarded as the target frequency.
* When one inverter compressor starts in the outdoor unit with 2 inverter compressors, only one inverter
compressor runs under the following conditions although the load becomes larger and a number of
compressors are needed to run in heating mode.
Type of outdoor unit
Minimum
frequency
(Hz) *1
compressor 1
compressor 2
compressor 1
compressor 2
Maximum
frequency
(Hz) *2
77.5
8HP
10HP
12HP
14HP
87.0
15
100.0
15
15
15
65.4
16HP
15
-
-
-
15
15
-
-
-
70.4
72.0
67.0
18HP
15
15
85.1
90.1
20HP
15
15
90.6
95.6
If the low pressure is over 1.6MPa during operation of the inverter compressor, the system is stopped.
(P27: Pre-trip)
1
Horsepower control (start & stop of compressor and increase & decrease of inverter frequency) are controlled
according to the numerical value of the pressure sensor installed at the outdoor unit and the temperature sensor
installed at the indoor unit heat exchanger.
* The pressure detected by the pressure sensor is converted to the saturated temperature.
There are two types of controls; one is the pressure detected by the pressure sensor and the other is detected
by the saturated temperature.
High pressure saturated temperature is converted from values detected by the high pressure sensor.
Low pressure saturated temperature is converted from values detected by the low pressure sensor.
1
If 2 inverter compressors are simultaneously operating in the same outdoor unit, the frequency of the
inverter compressor 1 becomes 5Hz lower than that of the inverter compressor 2.
3
2
1
3
2
System stopped → When operated for 3 to 5 minutes
Maximum discharge temperature of inverter compressor in whole system
＜
High pressure sensor
tempe10°C
Minimum discharge temperature of inverter compressor in whole system
＜
High pressure sensor
tempe5°C
48°C
43°C
20°C
10°C
2WAY VRF SYSTEM
Control Functions
3. Compressor Control
Once a compressor stops, it will not start for a period of 3 minutes (3-minute forced OFF).
However, this is not applied when the compressor was forced to stop as the result of a special control
operation. (Start control, Defrost control, Refrigerant oil recovery control, etc.)
(5) Forced Stopping of Compressor
(6) Horsepower Control (Roadmap Control)
Horsepower control (start & stop of compressor and increase & decrease of inverter frequency) are
controlled according to the numerical value of the pressure sensor installed at the outdoor unit and the
temperature sensor installed at the indoor unit heat exchanger.
* The pressure detected by the pressure sensor is converted to the saturated temperature.
There are two types of controls; one is the pressure detected by the pressure sensor and the other is
detected by the saturated temperature.
High pressure saturated temperature is converted from values detected by the high pressure sensor.
Low pressure saturated temperature is converted from values detected by the low pressure sensor.
1
This control is performed every 30 seconds.
* In the case that the compressor is stopped from such as special controls, load level does not turn to “0”
even if the indoor unit is most likely to be in stopped state.
Definition of evaporation temperature (Te)
Lowest temperature of all indoor units’ evaporation temperature (E1, E3) in the system including the
stopped indoor units
Definition of condensation temperature (Tc)
Highest temperature of all outdoor units’ high pressure saturated temperature
Load level varies from a minimum of 0 to a maximum of 30 on 1 to 1 basis up to 31 levels.
When the indoor unit stops (including thermostat OFF), the level shows “0”.
In the case of test run mode, the actual level implies “30” even if a PC monitor indicates “31”.
Load level increases when the differential temperature noted above indicates plus (+) value and
decreases when it indicates minus (-) value.
However, the types of units which are set to control the discharge temperature vary according to the
lowest value from the intake temperature difference and discharge temperature difference.
The indoor unit demand level varies according to the following 2 conditions.
Horsepower is controlled by the maximum value of all indoor units load level.
Intake temperature difference:
Difference between indoor unit remote control set temperature and intake temperature (TA)
Discharge temperature difference:
Difference between preset discharge setting temperature according to the type of indoor unit and
actual discharge temperature (TF)
2
When cooling operation, evaporation temperature (= antifreeze control) and condensation temperature
(= high pressure prevention control) are applied.
When heating operation, condensation temperature (= high pressure prevention control) is applied.
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16/08/26 19:23:14
