Series Multi-Melt Melting System

The IGBT is a composite device that combines the power transistor (GTR) and the power MOSFET. It integrates the advantages of both GTR and SFT, thus exhibiting excellent characteristics.

Technical Features

1. The IGBT is a composite device that integrates the power transistor (GTR) and the power MOSFET. It combines the advantages of both GTR and SFT, thus exhibiting excellent characteristics.
2. The IGBT intermediate-frequency power supply employs a circuit configuration in which capacitors are connected in series with the induction coil. Since frequency modulation and power regulation are used, the rectifier bridge operates in an uncontrolled state, resulting in a power factor of 0.96 or higher. Moreover, the operation generates minimal harmonics.
3. Compared to thyristors, IGBT transistors not only allow precise control over turn-on but also enable arbitrary and independent control over turn-off. Unlike thyristors, which rely on passive turn-off and require a certain amount of time to complete the process, IGBTs offer faster and more flexible switching, resulting in a higher inverter power factor (297%). With the same incoming line voltage (380V), the furnace voltage is significantly higher. The IGBT inverter operates at around 2800V, whereas conventional thyristor inverters typically reach only 750 to 800V at most—nearly four times higher. This higher voltage reduces line losses and allows for energy savings of up to 15%.
4. Constant Power Output: Compared to the traditional thyristor-based medium-frequency power supply, which adjusts voltage and power by regulating the firing angle, the IGBT-based medium-frequency power supply features frequency and power modulation that is largely unaffected by variations in charge quantity or furnace lining thickness. Throughout the entire melting process, it maintains an output power that is nearly constant. In contrast, during heating with a conventional thyristor-based medium-frequency power supply, the magnetic flux changes significantly, initially resulting in lower melting power and slower melting rates. The power output of the thyristor-based power supply varies with both melting time and magnetic flux—gradually increasing from low power to high power. This results in reduced utilization of transformer capacity and higher production costs. In this regard, the IGBT-based medium-frequency power supply can achieve energy savings of approximately 3% to 5%.

Product Advantages

High efficiency
The grid-connected inverter adopts a half-bridge circuit, which reduces the number of components in the main circuit and achieves a high power factor, thus delivering higher power output.
The device features excellent automatic characteristics, enabling smooth and reliable starting under full-load and heavy-load conditions with a 100% success rate. It improves the power factor to ensure that it remains at 95% regardless of the load level. The power output is maintained at a constant level, and during the melting process, even as the load and temperature fluctuate, the device consistently delivers full power output, thereby significantly reducing the melting time.
Equipped with a comprehensive protection and operational status monitoring system.
For example, sensors are used to acquire signals from the incoming line current, voltage, and circuit current and voltage, which are then fed into a dual-loop digital circuit for current limiting, voltage limiting, and repeated overcurrent and overvoltage protection. Additionally, there are protections for water temperature and water pressure. Both KK thyristors and KP thyristors feature self-turn-off time protection.
There is a complete testing system.
For the inverter, the operating temperature of the filter capacitors is monitored by a temperature switch. Once the cooling water temperature exceeds the set value or a water circuit fault occurs, an alarm is triggered and the power supply is cut off. The input of the power supply’s cooling water is controlled by a water pressure relay, while the output cooling water is monitored by a temperature switch that detects low voltage and overheating; in either case, an alarm is triggered and the power supply is shut off.