Maintenance of Water-Cooled Cables for Medium-Frequency Melting Furnaces
2022-05-24
The water-cooled cable in the medium-frequency melting furnace uses water cooling to efficiently handle the transmission of high currents within the smelting chamber. Installed between the capacitor bank and the induction coil, it ensures the smooth delivery of variable-frequency current, enabling the medium-frequency melting furnace to operate smoothly. However, if there’s an issue with the furnace’s water-cooled cable, the following malfunctions may occur:
1. The water-cooled cable of the medium-frequency melting furnace is part of the furnace's load circuit, as it connects directly to the induction coil of the medium-frequency melting unit. Since the medium-frequency melting furnace requires a furnace turn-over every hour—causing the water-cooled cable to move along with it—the cable is subjected to both tensile stress and torsional forces. Additionally, as the furnace tilts during operation, the cable bends and twists repeatedly, leading to fatigue cracking over time. During the cable failure process, most of the cable breaks first; subsequently, the remaining intact section—which continues to carry high power—quickly burns out under continued operation. At this point, the medium-frequency power supply generates a significant overvoltage. If the overvoltage protection system fails to function reliably, it can cause irreversible damage to the thyristors. Once the water-cooled cable completely severs, the medium-frequency power supply immediately shuts down and becomes inoperable.
Since water-cooled cables pose a risk of breakage, it is essential to inspect them for any warning signs of potential fractures. You can disconnect the water-cooled cable from the output copper busbar of the heating capacitor and use a multimeter (set to the 200Ω range) to measure the cable's resistance. Under normal conditions, the resistance should read zero; if the cable is broken, the resistance will show as infinite. When performing this test, make sure to position the furnace in its tilting mode, allowing the water-cooled cable to disengage completely and ensuring that the fractured section is fully separated—only then can you accurately determine whether the core has indeed broken.
2. It’s easy to spot electrical leakage in the water-cooled cables of a medium-frequency melting furnace. Simply check whether there are water seepage marks at the contact point between the water-cooled cable’s forehead collar and the water nozzle, or if the water-cooled cable hose shows any cracks. Additionally, be alert for metal debris—such as iron filings—that might come into contact with the hose, potentially causing it to overheat and burn through. If you notice any signs of damage, replace the hose immediately.
3. Check whether the water-cooled cable connections of the medium-frequency melting furnace are loose—especially ensure that the connecting bolts are tightly secured and not loose, as this could lead to poor contact and potentially damage the thyristors in the medium-frequency power supply.
4. Check whether the water passages in the medium-frequency melting furnace’s water-cooled cables are clear, ensuring proper circulation for cooling. Frequent blockages in the water lines can reduce cooling efficiency, causing the temperature of the medium-frequency furnace’s water-cooled cables to rise and eventually leading to cable damage. When inspecting the water-cooled cables, focus on observing the actual flow rate of the water—do not rely solely on high water pressure in the cooling circuit to determine that the system is functioning correctly.
Real-time News
—
2025-09-17