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176
Inspection item
(2) Smoothing capacitors
A large-capacity aluminum electrolytic capacitor is used for smoothing in the main circuit DC section, and an aluminum
electrolytic capacitor is used for stabilizing the control power in the control circuit. Their characteristics are deteriorated
by the adverse effects of ripple currents, etc.
The replacement intervals greatly vary with the surrounding air temperature and operating conditions. When the
inverter is operated in air-conditioned, normal environment conditions, replace the capacitors about every 10 years.
The appearance criteria for inspection are as follows:
1) Case: Check the side and bottom faces for expansion
2) Sealing plate: Check for remarkable warp and extreme crack.
3) Check for external crack, discoloration, fluid leakage, etc. Judge that the capacitor has reached its life when the
measured capacitance of the capacitor reduced below 80% of the rating.
Refer to page 174 to perform the life check of the main circuit capacitor.
(3) Relays
To prevent a contact fault, etc., relays must be replaced according to the cumulative number of switching times
(switching life).