Panasonic U-8ME1E8E Service Manual page 30

7. Oil Control
7-2. Oil level detection
The compressor oil in the crankcase is sent by bypass via a capillary tube to the low-pressure circuit. The
temperature detected by an oil sensor is used to determine whether it is oil (warm) or refrigerant (cold).
7-3. Self-separator oil recovery control
* When a low oil level (1 or 0) is detected, oil is recovered from the oil separator to the compressor though ORVR.
7-4. Inter outdoor units oil recovery control – utilizing balance tubes
* If the low oil level (1 or 0) continues, that outdoor unit (oil-receiving outdoor unit) receives oil from operating
outdoor units where the oil level is not low (oil-supply outdoor units whose all compressor oil levels are 2 or 1).
- Control at the oil-supply outdoor unit begins 3 minutes after an outdoor unit falls into low oil level state.
Oil supply is performed for a maximum of 5 minutes from each unit.
- When oil supply is ended, oil supply from that outdoor unit will not occur again for a period of [(No. of outdoor
units minus1) x 5 minutes]. In addition, oil supply is ended if the oil-receiving outdoor unit oil level changes to 2,
or if the oil-supply outdoor unit oil level becomes "0".
- The supply of oil is received from 1 unit at a time, in sequence, according to the order of priority of their inverter
compressors.
- Operation during unit refrigerant oil recovery
[1] Oil-receiving outdoor unit
ORVR turns ON and remains ON.
[2] Oil-supply outdoor unit
RPV turns ON and remains ON.
RPV bypass valve repeatedly turns ON and OFF according to a constant cycle.
*This oil recovery might be performed regardless of oil level according to operating condition.
7-5. System oil recovery control
Outdoor unit mode (cooling / heating) is not changed during system oil recovery control.
7-5-1. Start of system oil recovery control
-When one of the oil level of compressors is "0" and the oil level of other compressors which are in same outdoor
unit is "1" or "0", system oil recovery control will start.
* If one compressor oil level is "0" but the oil level "2" exists, this oil recovery is not performed.
System oil recovery control is performed
1 2
There is no oil level "2"
-When the system continues operation for a long time at half of the maximum system capacity, system oil
recovery control might be performed at regular intervals* regardless of oil level.
* The interval is able to set in EEPROM of the main outdoor unit.
0 1 1
1 - 23
Control Functions-Outdoor Unit
System oil recovery is not performed
1 2 0 1
There is oil level "2"
2WAY SYSTEM
2
1