Mitsumi electronic 55K Welding System User Manual


 
PROTECTIVE FUNCTIONS
181
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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. This is greatly influenced by the ambient
temperature and operating conditions. When the inverter is operated in an ordinary, air-conditioned
environment, change the capacitors about every 10 years.
Check the following:
1) Case (side faces and bottom face for expansion)
2) Sealing plate (for remarkable warping and extreme cracks)
3) Explosion-proof valve (for excessive valve expansion and operation)
4) Appearance, external cracks, discoloration, leakage. When the measured capacitance of the capacitor has
reduced below 85% of the rating, change the capacitor.
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Relays
To prevent a contact fault, etc., relays must be changed according to the number of accumulative switching
times (switching life).
5.3.8 Inverter replacement
The inverter can be changed with the control circuit wiring kept connected. Before replacement, remove the
screws in the wiring cover of the inverter.
1) Remove the mounting screws in both ends of the control circuit terminal block.
2) With both hands, 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.