Hitachi E-U Series Instruction Manual page 22

Type of Problem
Electromagnetic
switch turns off
Motor has overheated
Vortex Blower is
making a droning
sound
Vortex Blower is
making unusual or
excessive noise
Vortex Blower has
poor airflow
Rotation is reversed
Cause
Capacity of the
electromagnetic switch is
inadequate
Voltage has dropped or
become unbalanced
Foreign objects have been
inhaled, causing restriction
to the impeller.
Ambient temperature in the
installation room is
excessively high.
Stator coil short circuit
Improper gap spacing
between the stator and the
coil.
Metallic
If the sound is
there may be impeller
contact.
Rumbling
If the sound is
there may be damage to the
ball bearing.
There is a leak in the
piping.
There is a clog in the piping.
Power supply connection is
incorrect or backwards.
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Corrective Action
Correct or replace with a properly
sized the electromagnetic switch.
Contact the local power utilities
company.
Contact the local Hitachi
distributor for repair.
Improve the ventilation to the
room to lower the ambient
temperature.
Contact the local Hitachi
distributor for repair.
Contact the local Hitachi
distributor for repair.
,
Contact the local Hitachi
distributor for repair.
,
Contact the local Hitachi
distributor for repair.
Firmly tighten all joints.
Inspect and remove restrictions to
improve airflow.
Change the connections of two of
the three wires of the three-phase
power supply.