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5.3.6 Replacement of parts
The inverter consists of many electronic parts such as semiconductor devices.
The following parts may deteriorate with age because of their structures or physical characteristics, leading to
reduced performance or failure of the inverter. For preventive maintenance, the parts must be changed
periodically.
(
1
)
Cooling fan
The cooling fan cools heat-generating parts such as the main circuit semiconductor devices. The life of the
cooling fan bearing is usually 10,000 to 35,000 hours. Hence, the cooling fan must be changed every 2 to 3
years if the inverter is run continuously. When unusual noise and/or vibration is noticed during inspection, the
cooling fan must be changed immediately.
(
2
)
Smoothing capacitors
A large-capacity aluminum electrolytic capacitor is used for smoothing the DC in the main circuit, and an
aluminum electrolytic capacitor is also used for stabilizing the control power in the control circuit. Their
characteristics are adversely affected by ripple current, etc. When the inverter is operated in an ordinary, air-
conditioned environment, change the capacitors about every 5 years. When 5 years have elapsed, the
capacitors will deteriorate more rapidly.
Check the capacitors at least every year (less than six months if their life will be expired soon).
Check the following:
1) Case (side faces and bottom face for expansion)
2) Sealing plate (for remarkable warping and extreme cracks)
3) Explosion-proof valve (for excessive valve expansion and operation)
4) Appearance, external cracks, discoloration, leakage. When the measured capacitance of the capacitor has
reduced below 85% of the rating, change the capacitor.
(
3
)
Relays
To prevent a contact fault, etc., relays must be changed according to the number of accumulative switching
times (switching life).
See the following table for the inverter parts replacement guide. Lamps and other short-life parts must also be
changed during periodic inspection.
Replacement Parts of the Inverter
Part Name Standard Replacement Interval Description
Cooling fan 5 years Change (as required)
Smoothing capacitor in main circuit 5 years Change (as required)
Smoothing capacitor on control board 5 years Change the board (as required)
Smoothing capacitor on cooling fan power supply 5 years Change the power supply (as required)
Relays
Change as required