Maintenance of overcurrent faults in intermediate frequency furnace repairing intermediate frequency furnace
The over-current fault of the intermediate frequency furnace is the most common fault of the intermediate frequency intermediate frequency furnace. The phenomena are various and the reasons are also different. The main ones are: the overcurrent fault of the starting rectifier circuit power supply; the overcurrent fault of the inverter starting pre-magnetization stage Overcurrent fault after inverter switching. The following is an analysis of overcurrent faults of various phenomena, and the overcurrent protection action is initiated when the rectifier circuit power supply is started.
The main causes of such failures are:
The rectifying portion has a short circuit to ground or phase.There are more than two rectifier thyristors breakdown, resulting in a three-phase power supply phase-to-phase short circuit, which is accompanied by a huge current short-circuit explosion sound. In severe cases, the rectifier trigger board and the feedback signal board are also damaged.
The inverter initiates an overcurrent fault in the pre-magnetization phase. Such faults are generally caused by phase-to-phase short circuit at the load end, and when the intermediate frequency intermediate frequency furnace overcurrent protection action, there is a large current impact sound, which causes the overcurrent in the pre-charged phase mainly:
(l) The intermediate frequency furnace shunt compensation capacitor has a serious breakdown short circuit, causing phase-to-phase short circuit. Poor cooling water flow of the parallel capacitor or water loss may cause the capacitor to heat up and break down or breakdown due to quality problems of the capacitor itself, causing phase-to-phase short circuit.
(2) When such a fault occurs in the intermediate frequency furnace, it is possible to check whether the capacitor is swollen or whether it is hot by hand or not to determine which capacitor is broken. If you can't use this intuitive method to determine, you can only use the elimination method to remove the capacitors one by one, and then start the test to determine, in order to save time, you can split two or two.
(3) The copper-plated wire insulated frame of the intermediate frequency furnace is broken down, causing serious phase-to-phase short circuit.
(4) The connection of the shunt capacitors to the scorpion lines collides, causing a serious phase-to-phase short circuit.
