In the maintenance of the intermediate frequency melting furnace, the fault of the DC smoothing reactor is a fault that is difficult to judge and handle. The faults that occur in DC smoothing reactors are:
(1) The user randomly adjusts the air gap of the reactor and the number of turns of the coil, changes the inductance of the reactor, affects the filtering function of the reactor, and causes the DC current of the output to be intermittent, resulting in unstable operation of the inverter bridge. The inverter failed to burn the inverter thyristor. Arbitrarily adjust the air gap of the reactor and the number of turns of the coil. When the inverter bridge is short-circuited, it will reduce the ability of the reactor to block the current rise and burn the thyristor. Changing the inductance of the reactor at will also affect the starting performance of the intermediate frequency melting furnace;
(2) The reactor coil is loose. If the coil of the reactor is loose, the electromagnetic force causes the coil to shake during the operation of the intermediate frequency melting furnace, and the inductance is abrupt, which may cause the inverter to fail during light load starting and low current operation;
(3) The coil of the coil is not well insulated. Short circuit to ground or short circuit between turns, sparking discharge causes the inductance of the reactor to jump and strong electromagnetic interference, making the intermediate frequency melting furnace work unstable. The abnormal sound is generated frequently, and the thyristor is burned by the overcurrent, which causes the insulation of the coil insulation layer to be poor. The short circuit causes are:
a. The cooling is not good, and the temperature is too high, resulting in poor insulation of the insulation layer;
b. The reactor coil is loose, between the coil insulation layer and the coil insulation layer, between the coil insulation layer and the iron core, and the relative movement friction causes the insulation layer to be damaged;
c. When processing the scale of the reactor coil, the acid solution is infiltrated into the coil, and the acid solution corrodes the copper tube and forms a copper salt to destroy the insulating layer.
