Samsung AM080FX A Series Service Manual page 331

Piping Diagram
7-3 Functions (cont.)
7-3-2 Control (cont.)
7-3-2-5 Protective control (cont.)
Compression ratio protection
▪ Purpose
Prevent compressor damage due to abnormal operation.
Failure may occur due to an overload of compressors if the compression ratio is high.
Compressor failure may occur due to poor lubrication if the compression ratio is low.
▪ Concept
If the compression ratio is high, the compressor frequency is lowered to decrease the ratio.
If the compression ratio is low, the superheat degree for compressor suction is raised and the compressor frequency is increased. This
will increase the compression ratio.
Compression ratio = (High Pressure(kgf/cm2,g) + 1.03) / (Low Pressure(kgf/cm2,g) + 1.03)
▪ Control specifications in detail
- If the compression ratio is high,
1st step Hz hold : The current frequency is fixed. (It is possible to lower the frequency if necessary)
2nd step Hz down : The frequency is forcibly lowered by 5Hz at specified intervals.
3rd step HP down : The frequency is forcibly lowered by 1Hz every second.
Compression ratio
11.5
10.5
- If the compression ratio is low,
1st step Increase of the superheat degree : The superheat degree for compressor suction is increased .
2nd step Increase of the minimum compressor frequency : The minimum compressor frequency is increased to
3rd step Comp Trip : If in critical state for 10 min, stop the compressors and trigger an error (E428).
Compression ratio
8kgf/cm 2 ,g
△P
kgf/cm 2 ,g
△P
※△ P =Hig h Pressure –Low Pressure
Samsung Electronics
HP Down area
Hz Down area
Hz Hold area
9.5
Normal operation
Normal Operation
& 2.0
1.9
1.7
Cooling : Target SH 6 K & Target HP 28kgf/ cm
Heating : Target S H 4 K
or 1.5
Cooling : Minimum Hz increases if in this state for 3 min
Compressor trip (E428) occurs if in this state for 10 min
HP Down release
Hz D own release
the predefined model-specific frequency.
Min Hz release
SH control & Target HP release
2 ,g
Hz Hold release
350