Smoothing Capacitors - Mitsubishi Electric FR-XC-18.5K-PWM Instruction Manual

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 converter is operated in air-conditioned, normal environment conditions, replace the
capacitors about every 10 years.
When a certain period of time has 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).
End of life appearance criteria are as follows:
• Case: Check the side and bottom faces for expansion.
• Sealing plate: Check for remarkable warp and extreme crack.
• Top (vent): Check for swollen, open, or exploded vent.
• Others: Check for external crack, discoloration, liquid leakage, etc.
End of life performance criterion is the measured capacitance of the capacitor reduced below 85% of the rating.
Relays
To prevent a contact fault, etc., relays must be replaced according to the cumulative number of switching times (switching life).
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
Inspection item
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