DE597869C - Arrangement for switching off inductivities in direct current circuits - Google Patents

Description

It is known to put a capacitor in parallel to the switch contacts to extinguish the arc occurring at a switch. However, this arrangement has the disadvantage that when switching off ^r \ inductors on a relatively large capacitor is required and on the other hand, the switch contacts can be easily destroyed when closing the switch, since the capacitor discharges over the switch contacts. To avoid this disadvantage, one could put a liohen resistor in series with the capacitor. This also has the disadvantage that the capacity of the capacitor to erase is greatly reduced. In order to switch off inductances in direct current circuits, it is also known to connect a rectifier only in parallel with the inductance. With such an arrangement, however, as tests have shown, an electric arc still occurs, especially at currents above 1 Amp. If, however, according to the invention, a capacitor is placed parallel to the switch contacts in such an arrangement, the stability condition of the arc is definitely disturbed, so that sparking no longer occurs. This arrangement offers the advantage over the known arrangement in which only one capacitor is parallel to the switch contacts that the capacitor no longer needs to take up the entire energy of the inductance, so that it can be kept much smaller. For example, it would be necessary to put a capacitor of 2000 pF parallel to the switch contacts in a direct current circuit of 220 volts to switch off 1 kW with a time constant of the inductance of ο, ι seconds. In the arrangement according to the invention, however, only 2 «F are required. It is advisable to connect an ohmic resistor in series with the capacitor in order to reduce the discharge current of the capacitor. 45 '

Arrangements are known in which a rectifier is parallel to the inductance and parallel to the switch contacts an ohmic resistor. However, this known arrangement has the disadvantage that the ohmic resistance lying parallel to the switch contacts is a complete one Interrupting the circuit is not permitted; on the other hand, it will also cause a safe intervention of the rectifier is reduced.

In the figure, an embodiment of the invention is shown. 1 is the inductance (Choke coil, excitation coil of relays, switches, machines, etc.), which over the switch 2 is fed from the direct current source 3. Instead of the drawn Battery can also connect to a DC machine or a rectifier, the rectified Alternating current supplies the inductance. According to the invention, a rectifier 4 and at the same time are parallel to the inductance connected in parallel to the switch contacts a capacitor 5, which is an ohmic Resistor 6 is connected upstream.

A dry rectifier, for example, is expediently used as the rectifier a copper-copper oxide rectifier.

Claims (1)

Claim: Arrangement for switching off inductances in DC circuits, thereby characterized in that a rectifier is parallel to the inductance, which is the Interrupting the circuit allows the equalizing current to pass, and that at the same time, the switch contacts in the circuit are expediently interposed an ohmic resistance are constantly connected to the assignments of a capacitor. *) The patent seeker indicated the following as the inventors: Df.-Ing. Erich Friedländer in Berlin-Ruhleben and Dipl.-Ing. Dr. Jürgen v. Issendorff in Berlin-Siemens City. 1 sheet of drawings BERLIN. PRINTED IN THE REICHSDRUCKERET