This case study involves a medium frequency induction melting furnace, model WDL-KGPS-800, with a rated capacity of 0.8 tons and a maximum capacity of 0.96 tons, designed for aluminum melting applications. The equipment employs medium frequency induction heating and is equipped with a hydraulic tilting system for molten aluminum discharge. The electrical system is configured for a 380V/50Hz three-phase power supply, with a three-phase six-pulse rectifier and a parallel-connected inverter.
The core technical features of this equipment lie in the combination of the KGPS medium frequency power supply system and the steel-shell hydraulic tilting furnace body, representing a mid-capacity induction melting solution suitable for foundry shop operations.
The power supply system adopts the KGPS thyristor-based medium frequency power supply, which has matured through over a decade of continuous technological development. The rectifier section is a three-phase full-controlled bridge, with a medium frequency output voltage of 1500 volts, rated power of 500 kW, and an output frequency of 1000 Hz. The power factor exceeds 0.9, and the startup success rate is 100%, meaning medium frequency oscillation can be reliably established on every startup attempt.
The control circuit employs an eighth-generation digital circuit board architecture, featuring constant power control, swept-frequency zero-pressure soft start, and dual closed-loop voltage-current feedback. The protection system encompasses overcurrent, overvoltage, undercurrent, undervoltage, water loss, and phase-loss conditions. When any parameter exceeds the set threshold, the system automatically blocks pulse output and disconnects the main circuit power.
The power supply cabinet and capacitor cabinet are arranged separately. The capacitor cabinet provides medium frequency parallel compensation, improving system power factor and reducing reactive power transmission losses on the distribution lines. The capacitor bank capacity is matched to the resonant frequency of the induction coil, ensuring operation near the resonant point under rated conditions for optimal power output efficiency.
The induction coil is the core energy conversion component of the medium frequency furnace. When energized, the coil generates a strong alternating magnetic field that induces eddy currents in the metal charge within the furnace hearth, generating heat. The coil material is T2 copper with a wall thickness of 5 mm, constructed as a spiral tube. The coil design is based on finite element electromagnetic field analysis, with the deviation between actual operating power and design power controlled within 5%.
The coil employs advanced turn-to-turn insulation processing, with dedicated clamping technology to reduce axial vibration. The coil inner wall is coated with imported high-temperature-resistant insulating materials, and a furnace lining leakage alarm system is installed to detect molten aluminum seepage risks. A refractory coating of 10 to 15 mm thickness is applied to the inner surface of the coil, serving two functions: facilitating furnace lining construction and preventing thermal deformation of the lining that would affect service life.
The magnetic yokes are of crescent profile construction, laminated from cold-rolled silicon steel sheets and clamped with stainless steel splints. The contact surface between the yoke and the coil outer surface is curved, providing face contact rather than line contact, achieving better clamping efficiency and reduced magnetic flux leakage. The silicon steel sheets are reinforced with dedicated splints rather than through-bolts, maximizing the effective magnetic area of the sheets and reducing localized heating. The magnetic yokes serve to shield magnetic flux leakage, prevent furnace body heating, support and secure the induction coil, and improve overall system efficiency.
Furnace tilting is driven by a hydraulic system with two cylinders arranged on both sides of the furnace body for lifting. Furnace return is accomplished by gravity. The hydraulic station is equipped with dual motors and dual pumps – one in service and one on standby, with automatic switching capability. The fuel tank is fully enclosed and welded, with no openings except for the side and tubing ports, to prevent hydraulic oil leakage.
The hydraulic tilting console uses manual valve operation, with a tilting angle range of 0 to 95 degrees. Operation is smooth without shock or creeping, with adjustable speed and the ability to hold at any position. This design is suitable for casting applications requiring precise control of molten aluminum pouring volume.
The furnace shell adopts a steel-frame structure, comprising a fixed mounting base and a tilting furnace body, with the overall frame configuration ensuring rigidity. The hearth diameter-to-height ratio has been optimized through computer analysis, adopting advanced international furnace profile design principles – an increased ratio improves the natural power factor and enhances electrical efficiency.
An enclosed dust collection hood is installed above the furnace upper section to capture fumes and particulates generated during melting.
The crucible is of graphite construction, offering good chemical compatibility with aluminum melting. The crucible service life indicated in the proposal is 4 to 6 months, depending on operating conditions including charging method, melting temperature, and dross removal practices.
The water-cooled cables are constructed from TU1 multi-strand oxygen-free copper wire, sheathed in high-strength fire-resistant rubber tubing, with cold-formed connectors providing good electrical conductivity and tensile strength. The power supply side requires a cooling water flow rate of no less than 12 m³/h, while the furnace body side requires no less than 20 m³/h. The outlet water temperature on the power supply side must not exceed 35°C, and on the furnace body side must not exceed 45°C, with inlet water pressure maintained between 0.15 and 0.35 MPa. The water cooling system is equipped with a closed cooling tower, water tanks, and a control cabinet, forming an independent circulating cooling loop.
Rated capacity is 0.8 tons, with a maximum capacity of 0.96 tons, and a rated tapping temperature set at 780°C. Melting time is approximately 60 minutes per furnace, with a permissible deviation of ±5%. Based on this, the cycle from cold charging to reaching tapping temperature is approximately 1 hour, corresponding to a melting rate of approximately 0.8 tons per hour. With a rated power of 500 kW, the specific energy consumption is approximately 625 kWh per ton of aluminum, falling within the typical efficiency range for medium frequency induction melting furnaces.
This case study involves a medium frequency induction melting furnace, model WDL-KGPS-800, with a rated capacity of 0.8 tons and a maximum capacity of 0.96 tons, designed for aluminum melting applications. The equipment employs medium frequency induction heating and is equipped with a hydraulic tilting system for molten aluminum discharge. The electrical system is configured for a 380V/50Hz three-phase power supply, with a three-phase six-pulse rectifier and a parallel-connected inverter.
The core technical features of this equipment lie in the combination of the KGPS medium frequency power supply system and the steel-shell hydraulic tilting furnace body, representing a mid-capacity induction melting solution suitable for foundry shop operations.
The power supply system adopts the KGPS thyristor-based medium frequency power supply, which has matured through over a decade of continuous technological development. The rectifier section is a three-phase full-controlled bridge, with a medium frequency output voltage of 1500 volts, rated power of 500 kW, and an output frequency of 1000 Hz. The power factor exceeds 0.9, and the startup success rate is 100%, meaning medium frequency oscillation can be reliably established on every startup attempt.
The control circuit employs an eighth-generation digital circuit board architecture, featuring constant power control, swept-frequency zero-pressure soft start, and dual closed-loop voltage-current feedback. The protection system encompasses overcurrent, overvoltage, undercurrent, undervoltage, water loss, and phase-loss conditions. When any parameter exceeds the set threshold, the system automatically blocks pulse output and disconnects the main circuit power.
The power supply cabinet and capacitor cabinet are arranged separately. The capacitor cabinet provides medium frequency parallel compensation, improving system power factor and reducing reactive power transmission losses on the distribution lines. The capacitor bank capacity is matched to the resonant frequency of the induction coil, ensuring operation near the resonant point under rated conditions for optimal power output efficiency.
The induction coil is the core energy conversion component of the medium frequency furnace. When energized, the coil generates a strong alternating magnetic field that induces eddy currents in the metal charge within the furnace hearth, generating heat. The coil material is T2 copper with a wall thickness of 5 mm, constructed as a spiral tube. The coil design is based on finite element electromagnetic field analysis, with the deviation between actual operating power and design power controlled within 5%.
The coil employs advanced turn-to-turn insulation processing, with dedicated clamping technology to reduce axial vibration. The coil inner wall is coated with imported high-temperature-resistant insulating materials, and a furnace lining leakage alarm system is installed to detect molten aluminum seepage risks. A refractory coating of 10 to 15 mm thickness is applied to the inner surface of the coil, serving two functions: facilitating furnace lining construction and preventing thermal deformation of the lining that would affect service life.
The magnetic yokes are of crescent profile construction, laminated from cold-rolled silicon steel sheets and clamped with stainless steel splints. The contact surface between the yoke and the coil outer surface is curved, providing face contact rather than line contact, achieving better clamping efficiency and reduced magnetic flux leakage. The silicon steel sheets are reinforced with dedicated splints rather than through-bolts, maximizing the effective magnetic area of the sheets and reducing localized heating. The magnetic yokes serve to shield magnetic flux leakage, prevent furnace body heating, support and secure the induction coil, and improve overall system efficiency.
Furnace tilting is driven by a hydraulic system with two cylinders arranged on both sides of the furnace body for lifting. Furnace return is accomplished by gravity. The hydraulic station is equipped with dual motors and dual pumps – one in service and one on standby, with automatic switching capability. The fuel tank is fully enclosed and welded, with no openings except for the side and tubing ports, to prevent hydraulic oil leakage.
The hydraulic tilting console uses manual valve operation, with a tilting angle range of 0 to 95 degrees. Operation is smooth without shock or creeping, with adjustable speed and the ability to hold at any position. This design is suitable for casting applications requiring precise control of molten aluminum pouring volume.
The furnace shell adopts a steel-frame structure, comprising a fixed mounting base and a tilting furnace body, with the overall frame configuration ensuring rigidity. The hearth diameter-to-height ratio has been optimized through computer analysis, adopting advanced international furnace profile design principles – an increased ratio improves the natural power factor and enhances electrical efficiency.
An enclosed dust collection hood is installed above the furnace upper section to capture fumes and particulates generated during melting.
The crucible is of graphite construction, offering good chemical compatibility with aluminum melting. The crucible service life indicated in the proposal is 4 to 6 months, depending on operating conditions including charging method, melting temperature, and dross removal practices.
The water-cooled cables are constructed from TU1 multi-strand oxygen-free copper wire, sheathed in high-strength fire-resistant rubber tubing, with cold-formed connectors providing good electrical conductivity and tensile strength. The power supply side requires a cooling water flow rate of no less than 12 m³/h, while the furnace body side requires no less than 20 m³/h. The outlet water temperature on the power supply side must not exceed 35°C, and on the furnace body side must not exceed 45°C, with inlet water pressure maintained between 0.15 and 0.35 MPa. The water cooling system is equipped with a closed cooling tower, water tanks, and a control cabinet, forming an independent circulating cooling loop.
Rated capacity is 0.8 tons, with a maximum capacity of 0.96 tons, and a rated tapping temperature set at 780°C. Melting time is approximately 60 minutes per furnace, with a permissible deviation of ±5%. Based on this, the cycle from cold charging to reaching tapping temperature is approximately 1 hour, corresponding to a melting rate of approximately 0.8 tons per hour. With a rated power of 500 kW, the specific energy consumption is approximately 625 kWh per ton of aluminum, falling within the typical efficiency range for medium frequency induction melting furnaces.
