DE431942C - Circuit breaker for alternating current arc welding systems - Google Patents

Description

GERMAN EMPIRE

ISSUED JULY 26, 1926

REICH PATENT OFFICE

PATENT LETTERING

-JVl 431942 CLASS 21h GROUP 30

Siemens-Schuckertwerke G.m.b.H. in Berlin-Siemensstadt *).

Circuit breaker for AC arc welding systems.

Patented in the German Empire on April 21, 1925.

With transformers for arc welding the high no-load voltage dem Workers cannot become dangerous, according to a well-known proposal with the Primary winding of the transformer one

Choke coil connected in series which, when the secondary circuit is open, accounts for one part of the mains voltage throttled and short-circuited when current is introduced into the secondary circuit will. The short-circuiting is

* j The patent seeker indicated as the inventor:

Johann Schnepf in Nuremberg.

COPY

caused for example by a contactor through which the secondary current or primary current flows.

In welding systems with this protective circuit it has been observed that the ignition of the arc can cause great difficulties. Believed these difficulties have hitherto only been countered by using a relatively highly sensitive contactor to be able to. However, this would make the welding system unnecessarily expensive.

The invention overcomes this problem in a simple manner. In itself As is known, the inductor coil connected in series with the primary winding is used provided with an iron core. The dimensions of this core are according to the invention so dimensioned that the iron is already saturated by a current that is approximately the magnetizing current of the transformer is equal to.

In the drawing is the circuit diagram

such a system is shown for example.

α is the transformer, b the ballast

choke coil, c the contactor, d the welding electrode and e the workpiece.

If you use ordinary choke coils with a relatively large air gap and large iron cross-section, saturation only occurs at a current that is far greater than the magnetizing current of the transformer a. If current is introduced in the secondary circuit by touching the electrode d with the workpiece e , the primary current of the transformer α increases and with it the voltage drop across the inductor b . The primary terminal voltage of the transformer decreases with the result that the secondary voltage is not sufficient to excite a normal contactor sufficiently strong or to ignite the arc. *O

In the case of the invention, however, the voltage drop across the choke coil b remains practically unchanged even when the electrode and the workpiece are touched because of the saturation conditions. The primary terminal voltage of the transformer until contactor c responds is approximately the same as when it is idle. The increase in the secondary current does not cause any significant reduction in this terminal voltage. Even with an unfavorable surface condition of the workpiece e , the secondary current can therefore increase up to the strength required to switch on the contactor.

Claims (1)

-Claim: Circuit breaker for AC arc welding systems with one to the primary winding of the transformer in series with ferrous inductor and one with the primary or secondary winding of the transformer in series-connected contactor that responds when a current is introduced in the secondary circuit and the choke coil short-circuits, characterized by such dimensions of the iron core of the choke coil that a current ■ saturation is approximately the same as the magnitude of the magnetizing current of the transformer of iron. mm- CALM. PRINTED IN THE REICUSDRUCKIREI. COPY