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8. STANDARD COMPONENTS AND SUBSYSTEMS [Capacity Control System]
AUTO operation is 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.
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
Loading
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
150 minutes ?
Motor stops automatically
Less
than
specified
What is the plant
compressed air piping
pressure ?
10 seconds
or more
How long has
motor been
stopped ?
Less than
10 seconds
More than specified
15 minutes or more
Less than 30%
30% or more
Less than 15 minutes
YES
NO
I f 1 2 0 m i n u t e s o r m o re h a s
passed after the third stop, the
motor will continue to operate
for a minimum of 30 minutes
after restart of the air compres-
sor, and then return to the initial
150 minute cycle.
STV: Suction Throttle Valve
20Ux: 3-Way Solenoid Valve
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 restar t when the line
pressure is dropped to cut-in pressure.