Samsung AM072BXV Series Service Manual page 253

Piping Diagram
7-3 Functions (cont.)
7-3-2 Control (cont.)
7-3-2-4 Special operation modes (cont.)
Oil return operation
▪ Purpose
Perform oil return after a specified amount of time has elapsed in order to prevent an insufficient amount of oil in compressors.
▪ Concept
The compressor capacity is raised to increase the amount of refrigerant circulation. This will return oil remaining in indoor units and
piping.
▪ Control specifications in detail
- Oil recovery operation shall be performed to prevent a compressor from being short of oil. Oil in pipes or indoor unit will be col-
lected to outdoor unit by starting oil collecting operation.
- Oil collecting operation will begin 7 hours after outdoor unit starts to operate but time might be reduced depending on the operat-
ing condition (# of compressor in operation and operating frequency). Once defrosting operation operate for more than 3 minutes
during heating operation, it will be considered to have done oil collecting operation.
- Master outdoor unit will be changed after oil collecting operation.
Capacity of compressor
Indoor EEV
*Additional capacity = Compensation capacity of stop units
* EEV step can be varied by cycle condition.
Samsung Electronics
Actuator
Outdoor EEV
Outdoor Fan
Operating indoor units
Stopped indoor units
Indoor Fan
Time
Oil return Operation
Current capacity + additional capacity
Normal control
Normal control
Higher step of [400(C)/300(H) or Current step]
400(C)/300(H)
Normal control
3min(C) / 6min(H)
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