Piping Diagram
Samsung Electronics 350
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.
- 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
the predefined model-specific frequency.
3rd step Comp Trip : If in critical state for 10 min, stop the compressors and trigger an error (E428).
Compression ratio
Hz Hold area
Hz Down area
HP Down area
Normal operation
Hz Hold release
9.5
Hz D own release
10.5
HP Down release
11.5
Normal Operation
Cooling : Target SH 6 K & Target HP 28kgf/ cm
2
,g
Heating : Target S H 4 K
Cooling : Minimum Hz increases if in this state for 3 min
SH control & Target HP release
Min Hz release
Compression ratio
※△ P =Hig h Pressure –Low Pressure
△P kgf/cm
2
,g
or 1.5
1.7
1.9
△P 8kgf/cm
2
,g
& 2.0
Compressor trip (E428) occurs if in this state for 10 min
7-3 Functions (cont.)
7-3-2-5 Protective control (cont.)
7-3-2 Control (cont.)
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