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Precautions for Maintenance and Inspection
PROTECTIVE FUNCTIONS
6
(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 the life will be expired soon).
Check the following:
1) Case (side faces and bottom face for expansion)
2) Sealing plate (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 85% of the rating.
(3) Relays
To prevent a contact fault, etc., relays must be replaced according to the cumulative
number of switching times (switching life).