Hitachi UTOPIA RAS-4HVRP2E - Page 93

5 Control System
Protection control
SMGB0136 rev.0 - 07/2021
91
5
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P0A: Demand current control
The compressor operation frequency is controlled to set at the setting value of the outdoor unit inverter primary current
(40% to 100% of rated current of cooling operation). This function is detailed in the “External Input and Output Setting”.
Refer to the Service Manual for details.
Operating Conditions
The demand current control can be performed under the following conditions.
a. The demand signal is input from the centralized operation controller.
b. The demand signal is input at the external input terminals of the outdoor unit from external equipment such as a
building management system or a utility with a smart meter.
c. The demand function settings are set from the outdoor unit PCB.
d. The wave function is set from the outdoor unit PCB.
e. The demand signal is input from the indoor unit (wired controller).
If the operation current exceeds each setting function value, the compressor operation frequency is controlled.
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Priority of protection control
If two or more protection controls meet a condition, the protection controls perform according to the following.
Rank order Indication Protection control contents
1 P1 Pressure Ratio Control
2 P2 Pd Protection control
3 P3 Current Protection Control
4 P4 Control for prevention of the increase of Inverter n temperature
5 P5 Td increase protection control
6 PA Demand Control
7 P9 Pd decrease prevention control
8 P7 Inverter Trip Retry
9 P8 Insufcient Voltage/Open Phase Detection Retry
 Lower Rank Order of Protection Control Function
Forced
Decrease
Forced
Increase
Prohibited
Increase
Prohibited
Decrease

Higher Rank Order
of Protection Control
Function
Forced Decrease
   
Forced Increase
   
Prohibited Increase
   *1 
Prohibited Decrease
   
? NOTE
*1Dischargetemperatureincreaseprotectioncontrol(P5)ishigherthanthefollowingprotectioncontrols.
1 LowPressureDecreaseProtectionControl(P6).
2 DemandCurrentControl(PA).
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Degeneration control
The degeneration control is carried out to modify the protection control range. Prevents frequent ON/OFF caused by
alarm when retry stoppage by the abnormal control occurs.