KGCL Series One-to-Two Power Distribution Cabinet

Series rectification and series inversion technologies enable the production of 1-to-2 and 1-to-3 equipment configurations. One power supply can simultaneously power one furnace for melting and another furnace for holding and refining. Thus, such a system is equivalent to using two separate sets of equipment.

The thyristor-based medium-frequency power supply device, commonly referred to as a medium-frequency furnace, is a power supply device that uses the switching characteristics of thyristors to convert 50-Hz industrial-frequency current into medium-frequency current. It is widely used in fields such as induction melting, induction heating, and induction quenching.

Power Supply Series /Power Series  
The medium-frequency power supply cabinet is a core component of the entire system. Regardless of the type, a medium-frequency power supply always consists of two main parts: rectification and inversion. The rectification stage converts the 50-Hz AC power commonly used in our daily lives into a pulsating DC power. Depending on the number of rectification pulses, it can be classified into 6-pulse rectification, 12-pulse rectification, 24-pulse rectification, and so forth.  
After rectification, a smoothing reactor will be connected in series on the positive electrode.  
The function of the inverter section is to convert the DC power generated by rectification into a medium-frequency AC power.

Product Introduction /Product Introduction  
The series rectification and series inversion technologies enable the production of “one-to-two” and “one-to-three” equipment configurations. A single power supply can simultaneously power one furnace for melting and another furnace for holding and refining. This single set of equipment effectively functions as two separate units. The transformers exhibit high utilization efficiency, allowing users to save on transformer capacity costs by half. Thanks to the adoption of series rectification and series inversion technologies, the power factor remains consistently above 0.95, with no high-order harmonic pollution. All performance indicators meet the requirements set forth by the national power supply authorities, eliminating the need for reactive power compensation devices or harmonic mitigation equipment. Additionally, the induction coil current is low, and the melting time is shortened, resulting in a 20% reduction in electricity consumption. This makes it today’s most energy-efficient medium-frequency equipment with the highest power factor. Its performance metrics are leading both domestically and internationally, approaching the level of advanced international standards.

Working principle /Working Principle  
1) Rectifier circuit. Composed of six thyristors, this circuit is called a three-phase fully controlled rectifier bridge, commonly known as a six-pulse rectifier.  
The working principle involves sequentially controlling the turn-on and turn-off of corresponding thyristors at appropriate times according to a specific pattern, ultimately converting three-phase AC power into DC power.  
2) Filtering. Since the voltage rectified from the AC source fluctuates considerably, a large inductor needs to be connected in series within the circuit to smooth out the current and make the highly fluctuating voltage more stable. This process is known as filtering. Such an inductor is commonly referred to as a reactor. The key characteristic of a reactor is that it resists sudden changes in current.  
The relatively smooth DC current obtained after filtering is supplied to the inverter circuit. A series-connected capacitor is used to filter the device’s power supply, resulting in a smoother voltage.  
3. Inversion. An inverter circuit converts direct current into alternating current at a higher frequency to supply the load. Therefore, this type of inverter is essentially an “AC—DC—AC” converter, and its basic circuit is shown in the figure.  
4. Series resonance refers to the series connection of a compensating capacitor and an inductor.

 
The operating mode adopts a “one-to-two” configuration, meaning one rectifier power supply drives two inverter units. Alternatively, either of the two units can operate independently to supply power to Furnace No. 1 and Furnace No. 2. This dual-power, one-to-two functionality is particularly well-suited for large-scale, continuous production of small- and medium-sized castings. When one electric furnace is operating at high power for melting, the other furnace can either maintain heat or preheat a cold furnace. Power can be allocated flexibly according to demand, while the total power consumption of the two furnaces remains constant: Total power P_total = P1 + P2. By continuously alternating between melting and holding/feeding in these two furnaces while they run simultaneously, the power supply can always operate at full capacity. This operating mode—where one power supply powers two furnaces—greatly reduces the required transformer capacity. Taking a 5-ton furnace as an example, this approach can save up to 800,000 yuan per year in transformer capacity costs.  
 

Product Advantages /Product Advantages  
1. Energy-saving: The power supply boasts high efficiency, saving 20% more energy than conventional equipment.  
2. High efficiency: It produces no higher-order harmonics and boasts the highest power factor—exceeding 95%. There’s no need for reactive power compensation devices or harmonic elimination equipment. One power supply can simultaneously power one furnace for melting and another for holding and refining, resulting in high transformer utilization and allowing you to cut transformer capacity costs by half. With a “one-to-two” electric furnace setup, the two furnaces can either cast simultaneously or continuously supply molten steel for casting.  
3. Low failure rate; the relatively low operating voltage effectively ensures exceptional stability of power devices such as thyristors.  
4. Safety: Low harmonics and minimal grid pollution effectively ensure electrical safety.  
5. Excellent starting performance: The 1-to-2 electric furnace allows for flexible power distribution, with a 100% startup rate.

Auxiliary equipment /Auxiliary Equipment (Power Supply, Furnace Body, Cooling System)

 
The above diagram shows the standard configuration of a series-connected steel-shell furnace unit—one-to-one system, for reference only. Other types may have their configurations modified as needed.