Mitsubishi Electronics A800 Welding System User Manual


 
Inspection item
PRECAUTIONS FOR MAINTENANCE AND INSPECTION
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5
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:
Case: Check the side and bottom faces for expansion.
Sealing plate: Check for remarkable warp and extreme crack.
heck for external crack, discoloration, liquid leakage, etc. Judge that the capacitor has reached its life when the measured
capacitance of the capacitor reduced below 80% of the rating.
NOTE
The inverter diagnoses the control circuit capacitor by itself and can judge its life. (Refer to the FR-A800 Instruction Manual
(Detailed))
Relays
To prevent a contact fault, etc., relays must be replaced according to the cumulative number of switching times (switching life).
Main circuit fuse
A fuse is used inside the inverter. The replacement intervals vary with the surrounding air temperature and operating
conditions. When the converter unit is operated in air-conditioned, normal environment conditions, replace the capacitors
about every 10 years.
5.1.7 Inverter replacement
The inverter can be replaced with the control circuit wiring kept connected. Before replacement, remove the wiring cover of
the inverter.
1)Loosen the two mounting screws at the both side of the control circuit terminal block. (These screws cannot be removed.)
Slide down the control circuit terminal block to remove it.
2)Be careful not to bend the pins of the inverter's control circuit connector, reinstall the control circuit terminal block and fix it
with the mounting screws.
NOTE
Before starting inverter replacement, switch power OFF, wait for at least 10 minutes, and then check the voltage with a tester
and such to ensure safety.
Loosen the screws