SU43097A1 - Device for feeding an induction furnace - Google Patents

Description

For feeding furnaces without an iron core at high power, a higher frequency current can be used, and in some cases even a low current. This kind of current can be obtained from a special single-phase generator of increased frequency, which, however, greatly reduces the overall output of the device and, moreover, makes it necessary to use rotating machines that are very inconvenient in factory practice. Although it is possible to apply a frequency of about 50 periods with very powerful furnaces, this decrease still does not allow the furnace to be powered from the city network, since the furnace requires a single-phase current, and the networks are usually three-phase and do not allow that significant load per phase. which is required for the furnace.

The proposed device aims to supply the furnace without an iron core from the network without rotating transducers, for which purpose the current of the urban or regional network is transformed simultaneously both in frequency and in the number of phases.

In the hitherto known devices for feeding furnaces without an iron core from three-phase networks of normal frequency and without transforming into single-phase frequency transformation by using harmonics that are multiples

three, had no place; in the proposed device, such use is carried out due to a special method of switching on the windings of the furnace.

The drawing shows one of the diagrams that can serve this purpose.

According to the drawing, /, 2, 3 - reactors with highly saturated iron cores. Each of the reactors 7, 2, 3 is connected in series with the corresponding section 4, 5, 6 of the furnace winding without an iron core.

All three circuits consisting of a reactor and the corresponding furnace winding are connected by a triangle. With this kind of inclusion and the presence of significant saturation of reactors 1,2,3 along the chains of m / -4, 2-5 and 3-6, the current will flow with very clearly expressed odd harmonics.

The currents of the individual windings 4, 5n6 create as a result in the furnace the magnetic field of trebled frequency and other higher frequencies, which gives a sufficient thermal effect.

However, with the passage of current of the form due to the presence of reactors 7, 2, 3, the use of windings 4, 5, 6 will be small, why it is possible to improve the efficiency of the device using capacitors 7, 8, 9, which must be configured so the inductance of each of the windings 4, 5, b for the third harmonic is compensated. In addition, it is possible to switch on capacitors between points 10, 11, 12, and 13, 14.15 to create circuits tuned to other higher harmonics.

Finally, to improve the power factor of the entire device, it is possible to turn on capacitors 16, 17, 18 by both a delta and a star.

Preliminary of the invention.

Claims (3)

1. Device for feeding an induction furnace, without an iron core from a three-phase network of normal frequency without converting current into a single-phase one, characterized in that, in order to create in a high-frequency magnetic flux furnace by using harmonics that are multiples of three, the phase windings 4, 5, 6 of the furnace are located relative to each other and TaKj are turned on so that their magnetomotive forces are added and the magnetic flux component having a normal frequency is zero. 2. The form of the device according to claim 1, characterized by the use of reactors I, 2, 3 with highly saturated magnetic conductors connected in series with the phase windings, respectively 4, 5, b of the furnace. 3. When using the device according to claim 1, use of tanks 7, 8, 9 connected in parallel with windings 4, 5, b and tuned to the third or multiple harmonics.