Five hot keywords in the era of energy saving in induction melting furnace

The first keyword: 12-pulse double rectification

In order to reduce the harmonic interference generated by the intermediate frequency power supply to the power grid, the induction melting furnace adopts a 12-pulse thyristor bridge rectifier circuit. The transformer used for the rectifier circuit adopts the form of △/△ and Y wiring. The secondary side of the transformer has two sets of three-phase outputs. The voltages of the two sets of outputs are equal, all of which are 660V, but the phase difference is 30°. The two sets of outputs are connected to two sets of rectifiers. The usual intermediate frequency power supply uses a three-phase 6-pulse thyristor bridge rectifier circuit, which generates 5 times (250HZ), 7 times (350HZ), 11 times (550HZ), 13 times (650HZ) and higher. The second harmonic interference current, the magnitude of these harmonic currents is 1/5, 1/7, 1/11 and 1/13 of the power frequency fundamental current, respectively. When the output power of the intermediate frequency power supply is relatively large, if three-phase 6-pulse thyristor bridge rectifier circuits are used, the harmonic interference generated during their operation may cause the local power grid to exceed the standard or cause some precision equipment and instruments to fail. 

After adopting the six-phase 12-pulse bridge rectifier circuit, due to the special connection of the transformer, the 5th and 7th harmonic currents will cancel each other inside the transformer, and the harmonic interference to the power grid is greatly reduced. The minimum harmonic of the 12-pulse bridge rectifier circuit is 11 times, and the size is 1/11 of the power-frequency fundamental current. When a six-pulse thyristor bridge rectifier circuit is used, the input current of the transformer is a square wave, and the current contains more high-order harmonic components. The double-rectifier 12-pulse induction melting furnace adopts a 12-pulse thyristor bridge rectifier circuit. The grid input current is close to a sine wave with less harmonic components.

The second keyword: double rectifier parallel

That is to say, the two sets of rectification are in parallel relationship, and the parallel input line power supply voltage 660v-950v realizes the output of 0~1350V continuously adjustable DC voltage.

The third keyword: double rectifier series

It is a 6-phase 12-pulse fully-controlled bridge rectifier circuit that mainly rectifies 50 Hz AC to DC. A 12-pulse series full-controlled rectifier circuit consisting of 12 thyristors inputs the power frequency grid voltage (380V-660V) to control the conduction of the thyristor, and realizes a continuously adjustable DC voltage of 0~1150V.

The fourth keyword: series intermediate frequency electric furnace

Because the general-purpose induction melting furnace can not meet the energy-saving requirements, the high-performance series induction melting furnace meets the energy-saving requirements. The series intermediate frequency electric furnace rectification is divided into single rectification power supply (6-pulse intermediate frequency power supply), and dual rectification power supply (12-pulse intermediate frequency power supply) for series connection. Inverter operation. The power factor is always greater than 0.95, the harmonic content is small, the rectified output voltage is constant, and the waveform is good. Therefore, the operating efficiency of the device is high, and 10 to 20% of electric energy can be saved, and the energy saving effect is obvious.

The fifth keyword: one for two

A series resonant dual output power supply with two electric furnaces can work at the same time (commonly known as one to two), that is, the output power can be randomly distributed between the two furnace bodies, and the two furnace bodies can be simultaneously powered, one insulation , a smelt.

With the active implementation of national energy conservation and emission reduction and the gradual implementation of high-efficiency energy-saving induction melting furnaces, the energy-efficient induction melting furnace industry will usher in growth. In the next few years, the proportion of energy-saving one-two induction melting furnace equipment will account for more than 60% of domestic electric furnaces.