DE500840C - Arc welding machine for alternating current - Google Patents

Description

The present invention relates to an alternating current arc welding apparatus.

For electric arc welding you need z. B. 3 to 4 kW. Well have but all arc welding machines for alternating current have a very poor power factor, namely 0.25 to 0.45 depending on the level of the secondary open circuit voltage, so that its connection value is 16 to 9 kV A; Due to this high connection value, the spread is held back, since the single-phase Connection, which such devices require, to the public network only in rare cases and then only allowed at high tariffs.

In order to reduce the connection value, the lagging reactive current of the Compensate welding equipment by connecting one or more capacitors in parallel, and as with all apparatuses that consume more reactive current than reactive current, one only compensates to the extent that this is Devices do not consume more power when idling than at full load, otherwise a four- " Complication by relays, switches and the like would be necessary.

The diagram in Fig. 1 in the accompanying drawing shows how far you can go can compensate, whereby the magnetizing current of the feeding transformer is neglected.

In the figure, h

the direction of the active power, i the direction of the lagging reactive power, k the direction of the leading reactive power. The apparent power of the apparatus is assumed to be 9 kVA and drawn by the vector α at an angle φ corresponding to a cos φ equal to 0.4, α together with the leading reactive power, V gives the resulting power c or the connection value, which is 4.9 kVA becomes. The capacitor or capacitors must also have a power b = V. The fact that b = c, i.e. the apparent full load power is equal to the apparent no-load power, is shown by the circular arc e .

As I said, the magnetizing current of the transformer is neglected in Fig. I. In reality, normal welding machines have a magnetizing power of 5 »ι to 1, S kVA with an induction of 10,000 to 12,000 Gauss. In Fig. 2 the same conditions are shown as in Fig. 1, but taking into account a normal lagging magnetization power of I kVA. The resulting power m or the connection value is composed of the schematic power g of the apparatus (9 kVA) with a cos φ = 0.4 and the leading capacitor power / '. It will! t is dimensioned so that it equals: the magnetization power η plus the resulting power m . In the present case, wi is 4.5 kVA with the same active power (3.6 kW) as in Fig. 1. The capacitor power / '= 5.5 kVA, of which only the part / = 4.5 kVA = V - m comes into effect, as the circle e shows.

The invention now relates to an arc welding apparatus for alternating current which is fully or partially compensated by one or more capacitors and which is thereby is characterized in that its iron parts are unsaturated when loaded, but when idling are saturated.

Obviously, in this way the most extensive compensation can be achieved with minor

ίο means can be achieved, and among other things, a higher induction than 12,000 Gauss can be made available for the iron parts of the welding apparatus when idling.
The secondary coil is arranged in a known manner so that when a load is applied, a large part of the lines of force is passed through the air, as a result of which the iron parts of the transformer are unsaturated over most of their length.

With an induction that is greater than 12,000 Gauss, the magnetization power increases rapidly and can be driven to around 3 kVA without excessive heating of the laminated iron parts, instead of only ι to 1.5 kVA with an induction of 10,000 to 12 000 Gauss. By increasing the magnetization power in this way, however, the resulting power can be reduced even further, as can be seen in Fig. 2.

With a magnetizing power of 3 kVA z. B. the connected load equals 3.8 kVA, a value that even the smallest networks can withstand when connected.

Fig. 3 and 4 show two examples of the welding machine.

According to Fig. 3, the iron core p of the welding machine has the shape of a right-angled frame. The primary winding q , which is fed from the network t-ii and from which the capacitor is fed by means of a special winding w, an economy circuit, is arranged on one longitudinal leg. The connection in the manner shown has the purpose that the vibrations caused by the arc and transmitted to the primary side in the network can be compensated without damaging the capacitor r , since capacitors are known to be very sensitive to rapid vibrations and the overvoltages caused by them. This circuit is also advantageous because the capacitors are known to be more economical at higher voltages than at normal mains voltages.

On the other longitudinal leg of the iron core p , the secondary winding s is arranged, which feeds the arc, not shown.

Through the compensation and the simultaneous Saturation of the iron core while idling, the connected load of the welding machine is pushed down to about 3.8 kVA and the Power surges from idle to full load restricted, so that the public networks the Can allow connection without further notice.

In Fig. 4, a special separate winding y with a voltage of about 600 to 1000 volts is provided on the longitudinal leg of the iron core p on which the primary winding ί is arranged. The capacitor r is connected to this winding y, which, as indicated in the drawing Fig. 4, is separated from winding q to produce a throttling effect for the rapid oscillations.

Instead of just one capacitor r , several can be used.

Claims (2)

Patent claims: 1. Arc welding machine for alternating current, wholly or partially through one or more capacitors is compensated, characterized in that its iron parts are unsaturated when loaded, but are saturated when idling. 2. Arc welding apparatus according to claim i, characterized in that the or the capacitors to a special one that is spatially separated from the primary coil Winding are laid. 1 sheet of drawings BfeftLlN- PRINTED Itt DfeR