Hitachi UTOPIA RAS-4HVRP2E - Activating Condition of Protection Control Code

5 Control System
Protection control
SMGB0136 rev.0 - 07/2021
88
5.3.2 Activating condition of protection control code
To monitor the conditions such as the temperature change and others, the control of the frequency and other controls are
performed by the protection control in order to prevent the abnormal operations. The activating conditions of protection
control are shown in the table below:
Code Protection Control Remark
P1
Pressure Ratio Protection Control
To control the compressor frequency for prevention of operation with
high/low pressure ratio.
P2
High-Pressure Increase Protection Control
To control the compressor frequency for prevention of high pressure
increase.
P3
Inverter Current Protection Control
To control the compressor frequency for prevention of inverter
current increase in the outdoor unit during operation.
P4
Inverter Fin Temperature Increase Protection Control
To control the compressor frequency for prevention of inverter n
temperature increase. The inverter n temperature is detected at the
inverter PCB.
P5
Discharge Temperature Increase Protection Control
To control the compressor frequency for prevention of discharge gas
temperature increase during operation.
P9
High Pressure Decrease Protection Control
To control the compressor frequency for prevention of high pressure
decrease, which would interrupt smooth refrigerant distribution to
indoor units with different height and oil supply to the compressor.
PA
Demand Current Control
To control the compressor frequency for xing the inverter primary
current around the set value (40~100% of rated current for cooling).
P7
Inverter Trip Retry
To stop the unit operation temporarily for protection of the
compressor and inverter. The operation will be restarted or stopped
depending on the retry.
Insufcient Voltage/Open Phase frequency.
P8
Insufcient Voltage/Open Phase Detection Retry

P01: Pressure ratio increase protection control
a. Pressure Ratio Increase Protection Control.
It is performed in order to protect the compressor from an increase of pressure ratio.
7.07.0
7.0
7.5
7.5
A Normal operation
B
Not allowing frequency increases (only frequency decreases are
allowed)
C Frequency forced decrease (0.25Hz/sec)
? NOTE
• In order to carry out this control, the pressure ratio of each outdoor unit
is calculated.
Pressureratioε=(Pd+0.1)/(Ps+0.1)
Pd:Highpressuresensordetectedvalue(MPa).
Ps:Lowpressuresensordetectedvalue(MPa).
b. Low Compression Ratio Protection Function
This function is activated to protect the compressor during occurrences of low compression ratio.
D
1.8
1.6
1.6
1.8
1.5
A Normal operation
B
Not allowing frequency increases (only frequency decreases are
allowed)
C Forced increase in frequency (0.25 Hz/s)
D Abnormal Stoppage (cause of stoppage d1-11)
(1) for 1 minute
? NOTE
ԑ:pressureratio