How to deal with the problem of no magnetic force of the lifting electromagnetic chuck?

Lifting electromagnetic chucks often have such a phenomenon during operation: after long-term use, there will often be no magnetic force. How should we deal with it at this time? Let's briefly analyze it together.

When the lifting electromagnetic chuck is started, press the button of the grinding wheel motor to start the switch of the electromagnetic chuck, the workpiece cannot be attracted, and the contact of the relay is interlocked, and the grinding wheel motor cannot be started at the same time. 2-terminal electrical inspection, and then use a multimeter to measure the power supply voltage at 500V AC, which is 380V. Disconnect the main power switch, check whether the AC contactor is mechanically stuck, remove one coil lead of the contactor, and use a multimeter to electrically block the measuring coil The 2-terminal resistance, the needle indication is normal, which proves that the coil is good.

After the coil is connected to conduct electricity, remove the undervoltage relay shell, measure the resistance of the 2 terminals of the coil, and the needle can still be used normally. At this time, it means that the coil of the voltage relay can be used normally, and then check whether the relay is stuck. Then close Turn on the power switch, and check the exclusions in sequence according to the above conditions.