Maeda MK0003, Service Manual, Page: 321 / 348

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■ Replacements of end of life parts
The inverter is composed of many electrical parts including semiconductor elements. Secular changes will occur
on the following parts, due to the structure and physical properties. If ignored, the inverter performance will be
reduced, and may result in failures, so in order to avoid failures, periodical inspections are required.
Note) The life of the parts may be affected by the ambient temperature and the usage conditions. The following
lifetime of the parts is under normal environmental conditions.
1) Cooling fan
The life of the cooling fan which cools down the heating parts is approximately 30,000 hours (2 to 3 years under
constant operation). Replacements are required when abnormal sound or frequency is observed.
2) Smoothing capacitor
The aluminum electrolytic capacitors for smoothing on the main circuit DC part will be affected by the ripple
current, and the characteristics will decay. The design life is 10 years, but it is recommended that replacements
should be performed every 5 years when used under normal environmental conditions. Since they are attached
directly on the print board, the smoothing capacitors along with the print board shall be replaced.
[General Criterion for the Inspection Items]
- Whether there is any liquid leakage
- Whether the safety valve is open
- Measurements of electric capacity and measurements of insulation resistance
Note) The replacement cycle for each parts can be determined by checking the running time. Contact the branches
and offices of Thoshiba Industrial Products and Systems Corporation for replacements. For safety reasons,
customers shall never perform replacements of parts.
■ Standard replacement period of main parts
The replacement cycle of parts under normal usage environment/condition (ambient temperature, ventilation
conditions, weld time) is as the following table.
This replacement cycle is not the life of the parts, but is based on the failure rate according to the years being used.
Parts name
Standard
replacement years
Method of replacement and others
Cooling fan 2 to 3 years Replace with new item
Aluminum electrolytic capacitors for
smoothing on the main circuit
5 years Replace with new item
Relay contactor — Determine according to inspections
Aluminum electrolytic capacitors on the
print board
5 years Replace with new board
Extracted from “Guideline for General Inverter Periodical Replacements” (October, 2001 edition) Japan Electrical
Manufacturers’ Association.
Note) The life of parts varies depending on the usage environment.