Measure the contact resistance of the conductive loop in the closed state, check whether the loop has contact defects, whether the contact is good, the port has friction, and whether there is an oxide layer on the contact surface.
The contact resistance increases due to oxidation of the contact surface and poor contact tightening.When a large current flows, the temperature of the contact point increases, which further accelerates the oxidation of the contact surface and further increases the contact resistance.If it continues, serious accidents will occur.Therefore, the contact resistance needs to be measured frequently or periodically.
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