Hitachi NEXT Series Instruction Manual page 80

8. STANDARD COMPONENTS AND SUBSYSTEMS [Capacity Control System]
8.4.4 Capacity Control System
Air intake
Air Intake filter
1st-stage blowoff solenoid valve (1)
2nd-stage blowoff solenoid valve (1)
1st-stage
airend
2nd-stage blowoff solenoid valve (2)
Intercooler
2nd-stage
airend
8.4.5 Relationship between Air Consumption Rate and Capacity Control System
※ The value in ( ) is indicated for water-cooled type.
Rated
Air
Model pressure consumption
(%)
psi [MPa]
100 - 75 (65) 134 (136) - 108 (108)
55 kW
125 [0.86]
100 - 60 (50) 133 (137) - 80 (72)
75 kW
75 (65) - 5
55 kW
125 [0.86]
60 (50) - 5
75 kW
All
125 [0.86] 5 - 0
model
The air compressor supports the three (3) capacity control systems as shown above.
Depending on the varying air consumption, an appropriate system is automatically selected. For more information, see the
following page.
IMPORTANT
To change the pressure settings and the capacity control
3.4 2, 3.4.3, 3.4.4)
type. ( .
78
1st-stage blowoff solenoid valve (2)
Aftercooler
Check valve
Operating
Capacity control system
frequency (Hz)
① CPCS motor
speed control
82
② Two-step purge
control
66 (60)
③ Motor stop/
Main motor stop
restart control
Purging Air Flow and Action of Blowoff Solenoid Valve
Operation phase
Starting
Loading
Purging
Stop
Power Interruption
Blowoff
silencer
Pressure sensor
PS2
Air
discharge
Control
pressure
Cut-out
pressure
Cut-in
pressure
Cut-in
pressure
Blowoff solenoid Blowoff solenoid
valve (1)
Fully opened Fully closed
Fully closed Fully closed
Fully opened Fully closed
Fully opened Fully opened
Fully closed Fully opened
Pressure setting
psi [MPa] Capacity
control type
Example
Initial
of Lower
AUTO ON
125 [0.86] 120 [0.83]
AUTO OFF
AUTO ON
138 [0.95] 125 [0.86]
AUTO OFF
131 [0.90] 120 [0.83]
AUTO ON
131 [0.90] 120 [0.83]
valve (2)
VSDA
or
VSDB
VSDA
or
VSDB
VSDA