Svar:
High short-circuit currents and an unregulated closing with load is the most common reason for the contactor to weld. This is usually due to an insufficient pre-charge. Read more about Pre-charge here.
Excessive and high short-circuit currents can cause the contact bridge to lift and open due to the magnetic field generated by the current, called levitation. This can cause the contactor to weld because when the contactor bridge opens, micro arcing and extensive heating occur.
Breaking higher loads than the contactor is designed for, especially high inductance can cause the contactor bridge to weld.
Using silver oxide on the contactor pills increases the resistance to welding.
Read more about our contactors here.
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Jonas Falconer
