Haier MRV5-H - 6.4.6 High Pressure Protection; 6.4.7 Low Pressure Protection

65
6.4.5 Pump Down Operation
After the liquid refrigerant is retained in the gas-liquid separator, the refrigeration oil in the compressor is diluted
to reduce the lubricity, and can cause Liquid compression, which may damage the compressor. This control is to
prevent these situations happening.
Pump down operation for cooling
The outdoor unit frequency is 25%* rated frequency, the indoor LEV is fully closed, and other automatic control,
after running for a period of time, the exhaust superheat degree meets the requirements and then exits.
Pump down operation for heating
Outdoor unit frequency 25%* rated frequency, outdoor unit LEV fully closed, other automatic control, after running
for a period of time, the exhaust superheat degree meets the requirements and then exits
6.4.6 High Pressure Protection
In order to maintain normal cooling and heating operation, high pressure control is performed by a high pressure
sensor.
Limit the upper limitation of the compressor operating frequency and operating under a certain high pressure value
※1
Normal
operation
Normal
operation
SV1: ON
Protection stop
Compressor speed
*Restart after 5 minutes
upper limitation control
(Max. 30rps)
·< 21.7psi
·< 7.2psi
Error stop
Ps<14.5psi
≥ 21.7psi
·< 4.3psi
· ≥ 29psi
High pressure
switch OFF
Error stop
Pd=537psi
Upper limitation control
·>537psi
·&
·≤537psi
·When the limitation control is completed
Locked if it occurs 3 times in an hour
* Restart after 3 minutes
※
6.4.7 Low Pressure Protection
By SV1 and compressor operating frequency control to maintains the low pressure above a specied value.