Hitachi HISCREW 2000 Series - Page 32

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6. SYSTEM OF EACH COMPONENT [Capacity Control System]
6.2.2 I-Type Capacity Control
(Standard setting for S-type at delivery
from the factory)
This controls the capacity as a flow chart in the
right figure.
(1) When “pressure fluctuation cycle: t” is less
than 28 seconds, U-type (suction unload type)
control is adopted.
(2) When “pressure fluctuation cycle: t” is
longer than 28 seconds, I-type (integral un-
load type) control is adopted.
6.2.3 P-Type Capacity Control
(Standard setting for M-type at delivery
from the factory)
This controls the capacity as a flow chart in the
right figure.
(1) If “pressure fluctuation cycle: t” is less than
28 seconds, U-Type control (Suction Unload
Type) is adopted.
(2) If “pressure fluctuation cycle: t” is over 28
seconds and the air consumption is larger
than 30% of its rated capacity, I-Type control
(Integral Unload Type) is adopted.
(3) If “pressure fluctuation cycle: t” is over 28
seconds and the air consumption is less than
30% of its rated capacity, P-Type control (Mo-
tor ON-OFF Control Type) is adopted.
However, the number of stops the motor makes
is limited to 3 times during 30 minutes.
(4) When the I-type unloading operation contin-
ues for 3 minutes, the P-type capacity control
is activated.
In case of P-Type (Motor ON-OFF Control Type),
(1) The Motor will not start again for 45 seconds when
it stops.
(2) Install an external air receiver tank. If you fail to ob-
serve this instruction, the plant airline pressure may
critically drop within 45 seconds (or before the mo-
tor can restart). When you want to use the
ECOMODE function, select a larger air receiver
tank. For appropriate air receiver tank capacity, see
page 36.
IMPORTANT
0.69MPa
0.59MPa
Pressure
Tim
e
t=1 Cycle Time
CycleTime:t
onceevery
3minutes
t≥28 seconds
① ②
t<28 seconds
100
0
①
;;;;;;
;;;;;;
;;;;;;
② ② ②
Time
Load Factor %.
I-Type
Control
U-Type
Control
0.69MPa
0.59MPa
Pressure
Tim
e
t=1 Cycle Time
CycleTime:t
Suction
Throttling
Time
Q≥30%
t≥28 seconds
Q<30%
YES
t<3 minutes
NO
t≥3 minutes
②
③
t<28 seconds
100
0
;;;;
;;;;
;;;;
;;
;;
;;
;;;
;;;
;;;
①
①
② ② ②
③ ③
Flowchartof
P-typeCapacity
Control
NO
YES
Air Consumption Q
Number of Stops
Less than 3 within
30 minutes ?
onceevery
3minutes
Time
Load Factor %.
P-Type Control
I-Type
Control
U-Type
Control