Fujitsu AirStage AB12, Service Manual

Page: 54 / 199

1. Oil return solenoid valves
Individual oil return
Central oil return
Solenoid valve Application
Solenoid valve SV3
SV4
SV5
SV6
Compressor 1
Compressor 2
Compressor 3
Compressor 1/2/3
2. Oil sensors
The oil sensors determine the oil level.
Definition
of state
State 0
State 1
State 2
State 3
State 0
State 1
State 2
OFF
ON
ON
OFF
ON
ON
OFF
OFF
OFF
ON
The oil is filled up to oil sensor U (upper limit).
Oil sensor L (lower limit) cuts the oil level.
Abnormal state ("Oil level error")
The oil level is between oil sensor U
(upper limit) and oil sensor L (lower limit).
Oil sensor U
Oil sensor L
Oil sensor U
Oil sensor L Compressor upper limit oil level sensor
Compressor lower limit oil level sensor
Oil sensor
Sketch
Contents of
state
U L
Definition of oil sensor operation (oil sensor U/L)
Oil sensor U/L
3. Individual oil return control
When a compressor operates continuously for 1 minute or longer and the oil sensor satisfies any of the following
conditions in "State 1" or "State 2", the solenoid valve corresponding to the compressor turns on and controls oil return.
(1) The integrated operating time of each compressor has reached 15 minutes or greater
(2) Each compressor is stopped.
* When oil return starts, the integrated operating time for each compressor is reset.
4. Central oil return control
When any of the following conditions is satisfied, the central oil return solenoid valve SV6 turns on and central oil return
control begins.
(1) One or more compressors are operating and the integrated time in the "1 or more compressors operating" state
exceeds 15 minutes
(2) All the compressors were stopped from the "1 or more compressors operating" state.
Oil sensor LED
(Voltage detected before output) - (voltage detected after output) < 0.3V max.
Oil sensor LED
(Voltage detected before output) - (voltage detected after output) 0.3V max.
=
>
Oil sensor circuit output judgment standard Operation
5-10 OIL RETURN CONTROL
OIL
SEPARATER
OIL
SEPARATER
OIL
SEPARATER
COMP.1
COMP.2
COMP.3
SV3
SV4
SV5
SV6
There are two oil return controls, one is the individual oil return
and the other one is centralized oil return.
(1)
(2)
When each solenoid valve is turned ON, the oil return is
Oil level status is defined in accordance with performance
performed
of the oil level sensor.
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