Johnson Controls YVAHP036B21S, Engineering Manual

Page: 45 / 94

OUTDOOR UNITS
TC-16001-rev.5
2-27
(7) P9: High Pressure Decrease Protection Control
When decreasing high pressure, the compressor operation frequency is controlled by this protection
control for the following purposes.
• To prevent insufficient refrigerant supply to indoor units installed at different height locations.
• To keep the refrigerant oil supply in the compressor.
Pd: Detected Value of High Pressure Sensor [psi (MPa)]
< Details of Control >
(8) PA: 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.
< Cancellation Condition >
The input signal is stopped at each condition (a) to (e).
NOTE:
This function is not available when the compressor starts or during a defrost operation.
(9) Pd: Low Pressure Increase Protection Control
The compressor operation frequency is controlled to protect the compressor from suction pressure
transitional increasing.
Ps: Detected Value of Low Pressure Sensor [psi (MPa)]
< Details of Control >
Ps ≥ 189psi (1.3MPa)
Ps ≤ 187psi (1.29MPa)
Ps ≤ 180psi (1.24MPa)
Abnormal Stoppage
(Stoppage Cause d1-12)
Ps < 203psi (1.4MPa) for 1 min.
Normal Operation
Frequency Forced Increase
(0.125Hz/sec.)
Prohibition of Frequency Decrease
(Except Frequency Increase Only)
Ps ≥ 189psi
(1.3MPa)
Pd < 174psi (1.2MPa)
Pd < 145psi (1.0MPa)
Abnormal Stoppage
(Stoppage Cause d1-26)
Normal Operation
Frequency Forced Increase
(0.125Hz/sec.)
Prohibition of Frequency Decrease
(Except Frequency Increase Only)
Pd < 145psi (1.0MPa) for 1hr.
Pd > 218psi (1.5MPa)
Pd > 174psi (1.2MPa)