Oil Equalizing This Control; Refrigerant/Oil Recovery Control - Toshiba HFCR407C Service Manual

Item Operation explanation and applied data, etc.
5. Oil equalizing This control is to prevent oil reduction in the compressor between the outdoor units. This
control control is classified into two functions, one is an individual control in normal operation
which is performed by the master outdoor unit, and the other is a system control which is
executed when shortage has been detected in the oil level detection control.
This control is executed by open/close operation of solenoid valves SV3A, SV3B, and
SV3C, and has the following two patterns.
(1) Oil equalizing control 1
This is executed when the master outdoor unit has continuously operated for 30
minutes or more, and the result of the oil level detection judgment has been
adequate. If only one outdoor unit is present this control is not implemented.
(2) Oil equalizing control 2
This is executed to supply oil collected in the oil tank of each outdoor unit to the
outdoor unit of which the oil level has been reduced. When the oil level judgment
result of the master outdoor unit has been insufficient while the compressor of
master outdoor unit was ON, or when one of the slave outdoor units required oil
equalizing, this control is implemented. When only one outdoor unit is present this
control is not implemented.
6. Refrigerant/Oil (1) Oil recovery control in cooling mode, Refrigerant recovery control in heating mode.
recovery During cooling/heating operation, this is executed to recover the oil/refrigerant in gas
control crossover pipes or indoor units to the outdoor unit when, the compressor operation
is reduced, this also prevents stagnation of refrigerant in the outdoor heat exchanger
while low ambient cooling operation is performed. This control is managed by the
master outdoor unit.
1) Control conditions
• When compressor-ON status continued for 60 minutes.
• When the cooling thermostat-OFF timer has finished.
2) Contents of control
60 minutes after cooling/heating operation has been activated, the cooling/
heating indoor oil/refrigerant recovery signal is sent to the indoor controller. The
cooling thermostat-ON 60 minutes timer starts counting again. At the same
time, the indoor PMV minimum opening signal is also sent to the indoor
controller.
Outline of control
Outdoor unit
57
Remarks
• Controls to divert
oil to the inverter
unit in operation
• Normal oil
equalizing
operation.
• Recovery time:
Approx. 2 min to 6
min though it differs
according to the
system capacity.
11