Induction melting furnace maintenance checklist

Fault location	Failure performance	Reasons and inspection methods	Solution
Breaker failure	1. When closing, there is a sound of opening at the same time	1. The three-phase circuit breaker is short-circuited and cannot be closed (generally caused by the burning of the thyristor)	1. Replace the thyristor and check the short circuit
	2. Measure that the upper end of the circuit breaker has electricity and the lower end has no electricity	2. The undervoltage release is burned out or not closed	2. To ensure that the equipment is not short-circuited, you can first tie it with a string to make it unable to bounce
	3. There is no response and no sound when the power rises	3. The shunt coil is always closed, check whether the opening coil is energized when closing	3. You can disconnect the thread at one end of the coil first, use the mechanical opening, and then check the circuit after the production is finished.

		4. Thermal relay failure or action	4. You can disconnect the two terminals of the relay first, and check after the production is finished
		5. Mechanical failure	5. See if it can be closed manually, and check after production
Incoming line inductance	1. Tripping caused by short circuit and ignition of the inductor	1. Observe whether the inductor is sparking, or the distance between the turns of the coil is close	1. Knock on the coils that are close to each other, and insert insulating materials to separate them

	2. Burning KP thyristor caused by too few turns	2. Check the number of coil turns to see if there are too few	2. Replace the large inductance coil in time
KP thyristor for 12- pulse rectifier string	1. The two-stage DC voltage has a large unsteady swing, and the inverter cannot be started	1. Check whether the rectifier voltage equalizing resistor is damaged	1. Replace the voltage equalizing resistor, and when it is still swinging, you can combine the two bridge resistors into one bridge

	2. View KP SCR	2. Check whether the rectifier and anti-parallel diode is damaged	2. Replace the diode
KP SCR	1. The circuit breaker cannot be closed (top circuit breaker)	1. Check whether the KP SCR is burned out	1. Replace the thyristor
	2. Cannot start	2. Check whether the KP thyristor pulse lamps are all on and the brightness is the same	2. The brightness is not the same, by reason of 3 , . 4 bar checking is
	3. The noise is loud when the power is increased	3. Check whether the SCR circuit is normal	3. Two wires can be temporarily connected first, and the wires can be checked after the production is completed

		4. Check whether the resistance between rectifier SCR G and K is normal (usually 10-25R ), if it is abnormal, check whether it is a line problem or a SCR problem	4. Proceed to Article 3 for circuit problems , and the SCR problem should be replaced
Air core reactor	1. Because of the small inductance required for series reactors, hollow inductors are generally used, which reduces the weight and volume, and reduces maintenance costs, because the distance between the coil turns is long and the copper tube wall thickness is not prone to sparking and water leakage. Phenomenon

Reactor with iron core	1. Reactor ignition	1. Measure whether the resistance of the copper ring of the reactor and the iron core is short-circuited ( when the line is 380V , the resistance should be greater than 1K )	1. Disassemble the reactor to check which coil is short-circuited, and repair or replace it

	2. Cannot start	2. Observe whether there is water leakage in the reactor	2. Disassemble the reactor to check which coil is leaking for repair or replacement

	3. Trip when the power is increased when it can be started	3. Reduce the indoor light to observe whether there is a fire phenomenon	3. If there are no accessories temporarily and the reactor has many turns, the broken coil can be removed without affecting the operation of the machine, and it can be temporarily operated until the end of production