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Hitachi NEXT Series Instruction Manual page 55

Oil-free rotary screw air compressor
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■ Other Operating Precautions
(1) A thermal relay is not provided on the main circuit
of the inver ter-controlled DSP. Instead, the
electronics-type thermal relay is built into the
inverter for protecting the main circuit.
(2) Phase failure is only enabled immediately after
connecting the power. If a phase failure occurs
during operation, it is not detected and eventually
causes the inverter to overheat. Tightly fasten,
therefore, the cables/wires.
(3) Do not install a power-factor enhancing capacitor
on the motor side. Failure to obser ve this may
cause the inver ter's capacitors to receive the
larger charging current, resulting in a failure of
the inverter.
(4) In the cases that a phase advance capacitor
installed between power and the air compressor
opens and closes, a surge voltage may be
generated in the controller input side, which may
cause a controller failure. In such cases, install an
AC reactor shown in the right table between power
and the air compressor.
(5) If radios, TV sets, or any other electronics devices
are located around the air compressor, install the
HITACHI noise filters as specified in the right
table on the primary side of the air compressor.
7. WIRING [Connecting the Power Cable]
(5) The inverter in the starter is attached with a digital
operator for setting and operating the inver ter.
Hitachi has finished adjusting the digital operator to
the appropriate settings, before shipping the DSP
from the factory. Do not operate the attached
digital operator; other wise the inver ter may
malfunction and cause a problem.
Recommended AC reactor
90VA6N, 90VW6N
110VA6N, 110VW6N
Immediately after disconnecting the power,
the inverter is still live. Before servicing the
starter/control box, therefore, make sure that
the inverter's charge indicator is off or wait for
10 minutes after disconnecting the power.
Zero phase
Radio noise
filter for input
Noise filter
for inverter
AC reactor
Reduces the radio frequency
interference, etc.
Reduces the conductive
noise in the power cable
wiring by the inverter.
Reduces radiated noise
from the power cable.

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