A decrease in the melting speed of a medium-frequency tungku induksi is typically caused by three core reasons: decreased electromagnetic coupling efficiency, insufficient actual output power, atau excessive heat loss. For precise troubleshooting, a systematic analysis can be conducted from the following four technical dimensions.
1. Electrical and Power Supply System Abnormalities
This is the most direct cause of a drop in melting power. Although the rated power of the equipment remains unchanged, the actual effective power applied to the furnace hearth may be significantly reduced.
- Inverter or Penyearah Faults: The thyristors (SCR) are not fully conducting, or the parameters of the inverter circuit have drifted, preventing the DC voltage or medium-frequency voltage from reaching the rated value.
- Low Power Factor: The compensation capacitor bank is damaged or not fully engaged, leading to a significant increase in reactive power and a decrease in active power.
- External Power jaringan Fluctuations: Low incoming line voltage or insufficient transformer capacity prevents the equipment from reaching its design power at full load.
2. Furnace Lining and Magnetic Circuit Status
Induction furnaces rely on magnetic lines of force cutting through metal to generate eddy currents for heating; the physical condition of the furnace lining directly determines the thermal efficiency.
- Excessively Thick Lining: If a newly built lining is too thick, it increases the distance between the charge and the induction coil, leading to increased magnetic leakage and a significant drop in electromagnetic coupling efficiency. Khas, as the lining wears thinner, the melting speed will gradually increase.
- Inter-turn Short Circuit of the Induction Coil: Damaged coil insulation, burned bakelite posts, or excessive accumulation of metallic dust can cause the induction current to short-circuit between turns. This not only severely slows down the melting speed of iron or steel but also easily leads to equipment burnout.
- Yoke Faults: The function of the yoke is to concentrate the magnetic lines of force toward the furnace hearth. If the yoke’s top screws are loose and not fully tightened, or if the internal silicon steel sheets are aging and generating heat, it will cause severe magnetic field dispersion and a sudden drop in heating efficiency.
3. Charge Quality and Charging Process
Operating procedures and the physical characteristics of the materials themselves have a decisive impact on heat transfer efficiency.
- Charge “Menjembatani“: Improper charging (large pieces stuck in the upper part of the furnace, small pieces at the bottom) can result in the bottom metal already melting or even boiling, while the upper charge cannot drop down to contact the molten iron. This not only stalls the melting process but also easily damages the furnace bottom.
- Poor Charge Material: The surface of scrap steel or pig iron is covered with severe rust, pasir, or oil. These impurities not only consume a large amount of extra thermal energy during melting but also generate thick slag that blocks heat transfer.
- Low Packing Density: The size of the charge pieces is highly uneven, resulting in excessive void space. During the initial stage of induction heating, it relies on the short-circuit rings between the charge pieces to conduct electricity and generate heat. Excessive voids often lead to poor induction loops and extremely slow initial melting.
4. Obstructed Cooling Water System
The equipment’s self-protection mechanism will automatically limit power when cooling is poor.
- Scaling in Water-Cooled Cables or Coils: Hard water causes scaling inside the water-cooled cables or the inner walls of the copper tubes, significantly reducing water flow. Once the water temperature rises, the system’s temperature sensor will trigger reduced-power operation or directly sound an alarm and shut down the machine.
Troubleshooting Recommendations
It is recommended to first observe whether the DC voltase, medium-frequency voltage, and incoming line current on the meter cabinet can reach full-load standards. If the electrical parameters are normal, focus on checking the packing density of the charge and the thickness of the lining; if the parameters cannot be reached, it is necessary to shut down the furnace to inspect the capacitor cabinet and thyristor status.
