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Algorithm & Control
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2.18.3 Limit Rotation
Determine from
•
Upper limit rotation
A minimum value was determined among the upper limits rotation, i.e. protection controls.
•
Lower limit rotation
A maximum value was determined among the lower limits rotation, i.e. protection controls.
Generally, compressor rotation is controlled within 5 zones: stop, drop, keep, up and reset subjected to a
particular operating temperature/current/pressure.
Zone
Control
Stop
Compressor is stopped when a certain limit reaches the stop zone for abnormality
correction.
Drop
Frequency will be dropped with a timer setting.
Keep
Frequency is maintained at lower/upper limit.
Up
Frequency will be increased with a timer setting.
Reset
Frequency lower/upper limit is canceled and returned to command rotation.
2.19 Defrost Cycle
Defrosting is carried out by the cooling cycle (reverse cycle). The defrosting time or outdoor heat exchanger
temperature must be more than a certain value to finish defrosting.
During defrost
All models
Compressor
ON
4-way valve
OFF
EXV in operation room
Fixed opening
Outdoor fan
OFF
Indoor fan
OFF
Conditions for starting Defrost
• The starting conditions are determined with the outdoor temperature and the outdoor heat exchanger
temperature
• The system is in heating condition
• Compressor minimum run time – 6 minutes OR
• More than A minutes (depending on the duration of the previous defrost control) of accumulated time
have passed since the start of the operation, or ending the previous defrosting
Condition for terminating defrost
The judgment is made with the outdoor heat exchanger temperature (
B
°C )