Pid Control; Operation Control Of Small Capacity Indoor Units; Control Flow - Daikin VRV II Series Technical Data Manual

1 Creating maximum comfort
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PID control

Proportional Integral Derivative control with an automatic capacity balancing circuit:
– enables the use of lengthy piping up to 100 meters (actual length)
– consists of two control systems:
1 Oil control system that controls the refrigerant oil volume to prevent it from raising or backing up in the pipes
2 Refrigerant flow stabilization mechanism: prevents refrigerant drift, caused by level difference of indoor units in the same system.
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Operation control of small capacity indoor units

If the operating frequency is minimal, the refrigerant pressure and outdoor temperature are detected, the number of control steps are calculated, and
capacity of outdoor unit heat exchanger (refrigerant accumulates in coils) and air flow of outdoor unit fans (controls pole change of the two fans) are
controlled.
If operating a small-capacity indoor unit, the bypass valve is controlled (ON/OFF), with capacity control being executed at a minimum of 14% for a 5HP
outdoor unit (when operating one 20-class indoor unit), or a minimum of 8% for 8 and 10HP outdoor units (when operating one 20-class indoor unit.
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Control flow

• VRVII & VRV-WII features
Minimum Frequency
(5HP Outdoor Unit: 30Hz)
(8/10HP Outdoor Unit: 30Hz)
Detection of Refrigerant Pressure and Outdoor
Temperature
Step Control Calculation
Capacity Control of Outdoor Unit
Heat Exchangers
Air Flow Control of Outdoor
Unit Fans
Are you operating a
small-capacity indoor unit?
Bypass Valve On/Off Control
Sampling Timer Count
Operating Pressure Detection by Pressure Sensors
Calculation of Constant for Integral Control
Total capacity Decision by Multi-Variable P-Control
Optimal Load Decision
Frequency Alteration of Inverter Compressor
On/Off of ON/OFF Compressor
No
Minimum Frequency
• Systems • VRVII & VRV-WII features
No
Yes
Every T Seconds
Deviation (difference between
sensed pressure and desired value)
Outdoor Coil Capacity
Control Air Volume
Control by Outdoor
Unit Fan
Step Control
Calculation
Detection of
Yes
Refrigerant Pressure
and Outdoor
Temperature
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