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8. STANDARD COMPONENTS AND SUBSYSTEMS [Capacity Control System]
15 sec or
more
STARTING UNLOADING RELOADING STOPPING
Suction throttle valve (STV) closed
START button ON
Airend starts rotation to
compress minor amounts of air
Starts in no load
Changes to full voltage
delta connection
3-way solenoid valve (20Ux)
switched over to connect
Chamber (A) & Chamber (C)
Suction throttle valve (STV) opens
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Air demand decreases
Discharge pipe pressure rises
Pressure sensor (PS) operates
3-way solenoid valve (20Ux)
switched over to pressurize
Chamber (A)
Suction throttle valve
(STV) closes
Blowoffvalve opens
Internal air in discharge
pipe is exhausted to
atmosphere
Air demand increases
Discharge pipe pressure drops
Pressure sensor (PS) operates
3-way solenoid valve (20Ux)
switched over to pressurize
Chamber (B)
Suction throttle valve
(STV) opens
Blowoff valve closes
Loading
3-way solenoid valve (20Ux)
switched over to pressurize
Chamber (A)
STOP button ON
Suction throttle valve
(STV) closes
Blowoff valve opens
Internal air in discharge
pipe is exhausted to
atmosphere
Compressor stops
Load-Unload Operation
AUTO Operation
How long has
motor been
running ?
Load ratio ?
Has motor stopped and
restarted 3 times or more for
90 minutes ?
Motor stops automatically
Less
than
specified
What is the plant
compressed air piping
pressure ?
How long has
motor been
stopped ?
Less than
15 seconds
More than specified
10 minutes or more
Less than 30%
30% or more
Less than 10 minutes
YES
NO
If the third stop is done after 70
minutes or more has passed
after the first stop, the motor
continues to operate for 20
minutes after restart of the air
compressor, and then return to
the initial cycle.
STV: Suction Throttle Valve
20Ux: 3-Way Solenoid Valve
AUTO operation is the Auto start - stop function in
addition to a standard on-off line, 0% or 100% capacity
2-step control. The CPU on the PC board is continually
calculating a load ratio.
8.4.2 AUTO Operation (Only for Fixed Speed Type)
When the load ratio is less than 30%, CPU stop the main
motor. And automatically restart when the line pressure
is dropped to cut-in pressure.
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