(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 also 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 ambient 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 : the side and bottom faces for expansion
2) Sealing plate : check for remarkable warp and extreme crack
3) Explosion-proof valve : check for excessive valve expansion and operation
4) 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.
The capacitor life alarm is output to give an indication of replacement time. (Refer to page 182.)
To prevent a contact fault, etc. relays must be replaced according to the cumulative number of switching
times (switching life).
The inverter can be replaced with the control circuit wiring kept connected. Before replacement, remove the
screws in the wiring cover of the inverter.
1) Remove the installation screws in both ends of the control circuit terminal block.
2) Pull down the terminal block from the back of the control circuit terminals.
3) When installing the terminal block to a new inverter, exercise care not to bend the pins of the control circuit
terminal block connector.
PRECAUTIONS FOR MAINTENANCE AND INSPECTION