Johnson Controls YVAHP036B21S, Engineering Manual

Page: 42 / 94

OUTDOOR UNITS
2-24
TC-16001-rev.5
Protection Control
(1) P1: Pressure Ratio Protection Control
(a) Pressure Ratio Increase Protection Control
Pressure Ratio Increase Protection Control is performed in order to protect the compressor from an
increase of pressure ratio.
< Details of Control >
NOTE:
The pressure ratio is calculated as follows.
e = (Pd [psi]+15) / (Ps [psi]+15)
e = (Pd [MPa]+0.1) / (Ps [MPa]+0.1)
Pd: Detected Value of High Pressure Sensor [psi]
Ps: Detected Value of Low Pressure Sensor [psi]
e > 7.0 e < 7.0
e > 7.5 e < 7.5
Normal Operation
Frequency Forced Decrease
(0.25Hz/sec.)
Prohibition of Frequency Increase
(Except Frequency Decrease Only)
< Indicated Contents >
Indication Protection Control Contents
P1 Pressure Ratio Protection Control
P2 High Pressure Increase Protection Control
P3 Inverter Current Protection Control
P4 Inverter Fin Temperature Increase Protection Control
P5 Discharge Temperature Increase Protection Control
P6 Low Pressure Decrease Protection Control
P9 High Pressure Decrease Protection Control
PA Demand Current Control
Pd Low Pressure Increase Protection Control
(b) Low Compression Ratio Protection Function
This function is activated to protect the compressor during occurrences of low compression ratio.
< Details of Control >
* Whenever protection control sequences are activated, the corresponding code is displayed on the
7-segment LED array of the main control board.
* Protection control code is displayed while a function is working, and goes out when released.
e
< 1.8
e
> 1.8
e < 1.6 e > 1.6
e < 1.5 for 1 min.
Normal Operation
Frequency Forced Increase
(0.25Hz/sec.)
Prohibition of Frequency Decrease
(Except Frequency Increase Only)
Abnormal Stoppage
(Stoppage Cause d1-11)