SU1687392A1 - Power source of plasma-arc machining apparatus - Google Patents

Abstract

The invention relates to mechanical engineering and is intended to power plasma arc installations. The purpose of the invention is improving the process stability, reducing the weight and size characteristics and increasing the efficiency of the power source. The source contains a single-phase transformer with two secondary windings located on the core in areas with different magnetic scattering. The first winding, located in the zone of less dissipation, is connected to the rectifier through a capacitor bank. The second winding is connected directly to the rectifier. The outputs of both rectifiers are connected to the arc gap. Such inclusion of rectifiers allows to obtain the maximum value of the constant component with equal currents in the windings. The invention makes it possible to reduce the magnitude of the pulsation of the plasma current by adding the currents of two rectifiers that are phase shifted relative to each other 2 silt (L

Description

The invention relates to mechanical engineering and is intended as a power source for flame-arc installations.

The aim of the invention is to increase the stability of the plasma-arc processing process by providing a power source with a steeply dipping external characteristic, as well as reducing the weight and size characteristics with a simultaneous increase in efficiency.

Figure 1 shows a circuit diagram of a power source; figure 2 - its current-voltage characteristic.

The power source consists of a single-phase transformer 1 containing one primary 2 and two secondary windings 3 and 4.

The first secondary winding 3 is located in the zone of small magnetic scattering and through the battery 5 of capacitors is connected to the first rectifier 6. The second secondary winding 4 is connected to the additional second rectifier 7, First 6 and second 7 rectifiers with their positive outputs connected through limiting resistor 8 to the nozzle 9 of the plasma torch 10. The minuses of both rectifiers are connected to the electrode 11 of the plasma torch 10.

The power source allows plasma-arc processing (mainly cutting) with high quality on various materials. In addition, the inclusion of capacitors in the secondary winding allows them to be used as for shifting

about

00 XI

with you

phases, and to increase cos f rectifier.

The power source works as follows.

After switching on the primary winding 2 into the network (U 220 V, f 50 Hz), the outputs of the rectifiers 6 and 7 are set to constant voltages close in magnitude to the amplitudes of the no-load voltage of the respective windings, and the amplitudes are almost equal.

The current consumed by the primary winding is determined by the losses in the core of a single-phase transformer 1 and the leakage currents of the rectifier valves 6 and 7.

Upon initiation of the arc discharge between the cathode and product 12, the voltage at the source output will be set equal to the arc voltage. In this case, currents will flow through the secondary windings 3 and 4

| 3 V2 (UBX - Uvih) W S

, (UBX-IW) a) L

(one)

where w With - the reactance of the battery capacitors 4;

W L-reactance winding 3.

The inductance of the second secondary winding 4, located on the core of the transformers in the large scattering zone, is determined by the high flux linkage value (Vfcac.) Of the distance L Sc (2).

four

The optimal mode of operation is the mode in which the currents through the secondary windings 3 and 4 are equal, i.e. at

Uh

one/

inductive resistance of the second secondary winding 4, equal to the capacitive impedance of the battery 5 capacitors. This mode allows you to get the maximum

the magnitude of the constant component of the current, since the currents in the inductance and capacitance are shifted by a quarter of the period and at the output of the rectifiers are added so that the minimum of the capacitive current coincides with the maxima of the inductive current and vice versa

The power supply is economical due to the high efficiency and reduced weight and size characteristics. In addition, a steeply dipping external characteristic improves the quality of plasma processing.

Claims (1)

Claims of the Invention A power source in plasma arc treatment installations comprising a single-phase transformer containing primary and first and second secondary windings, the first of which is connected to the first rectifier through a capacitor bank, and the second directly to the second rectifier, and the rectifiers are connected in parallel to the arc gap, characterized in that, in order to increase the stability of the plasma-arc processing process, increase reliability with simultaneous decrease in mass and size characteristics and increase efficiency; it is equipped with a limiting resistor for connection to a plasma torch nozzle connected to the positive terminals of the rectifiers, the first secondary winding located in the zone of small magnetic scattering and the second secondary winding neither 1 5 10 15 20 25 30 35 40 45 50 5560 Fig.Ј