Permanent magnetism

In recent years, machine of pneumatics of screw of permanent magnetism frequency conversion because its the characteristic such as stability of efficient, energy-saving, pressure gets the reliance of increasing client. But company of production of electric machinery of the permanent magnetism on market is uneven, if the choice is undeserved, bring about permanent magnetism electric machinery likely to break the risk of magnetism, and once permanent magnetism electric machinery breaks magnetism, basically can choose to change only electric machinery, bring about maintenance thereby cost is big. So, whether to judge permanent magnetism electric machinery to break magnetism? 1. The electric current when the machine is beginning to move is normal, in the course one