29
①
Checking the operating temperature
If the LCD monitor indicates main motor overload
[OVERLOAD: MAIN] (fixed speed type) or temperature
increase of main motor fin [FIN-T] (Vtype), investigate
the cause of the excessive heat and utilizing the
Motor
Diagnostics and Troubleshooting
chart below.
②
Cleaning
Clean the motor periodically to prevent dust
particles from accumulating inside and outside of
the motor.
When servicing the air compressor,
measure the insulation resistance of the motor
coil with a 500V megohmmeter and verify that
the insulation resistance is 1M
Ω
or more.
③
Disassembling
In a severe environment (dirty, corrosive, high dust
or high powder), disassemble and service the motor
every two years. In a normal environment, disassemble
and service the motor every six years. For the most
common motor problems, see the
Motor Diagnostic
and Troubleshooting
chart below. If the problem
cannot be solved with the chart, contact the local
HITACHI distributor/master dealer or representative
office.
Motor Diagnosis and Troubleshooting
4.11 Maintenance of Main Motor
Phenomenon
Cause
Excessive Sound
Excessive Rotation
Excessive V
ibration
Heated
Overload Indication
Breaker T
ripped
Electric Leak
Low Insulation Resistance
Corrective Action
Frame
Bearing
Installation
Loose bolts
○
◎
○
Retighten the bolts.
W
iring
Poor grounding
◎
Ground properly.
Inadequate breaker capacity
Note 3
○
◎
Replace with properly specifi ed capacity breaker.
Broken wires
○
Install new wires.
Failed breaker, controller or contactor
○
Note 3
○
Check the contacts and replace if necessary.
Environment
Dust accumulation reduced cooling
performance
○
Properly clean motor.
Excessive ambient operating
temperature
◎ ○ ◎
Improve the room ventilation or contact the local
Hitachi distributor.
High humidity
◎
Contact the local Hitachi distributor.
Large external vibration/shock
◎
Take vibration and shock measurements.
Power Supply
Phase-lacking operation
◎ ◎ ○ ◎
◎ ○
Check the brealer, contactor and motor wirings.
Widely dropped voltage
○ ○
◎
◎
Check the wire thickness and length and contact the
local power utilities company.
Fluctuating voltage
○
○ ○
○
Contact the local power utilities company.
Load
Overload
○
◎
◎ ○
Check the capacity control system.
Thrust force by the machine
○
○
◎
Check the contact condition of bull gear and pinion gear.
Excessive bearing noise NOTE 2
◎
◎
◎ ○
Contact the local Hitachi distributor.
Burnt motor coil NOTE 2
○ ○
○
◎ ◎ ◎ ○
Contact the local Hitachi distributor.
NOTES)
1.
◎
: Close relationship between the cause and type of problem.
〇
: Relationship between the cause and type of problem.
2. Detect the fundamental cause of the problem and take corrective action.
3. Breaker, controller or contactors are hot.
