DE1025496B - Current and voltage limitation in electrostatic painting and electrostatic filter systems - Google Patents

Description

GERMAN

The patent 870 874 relates to the use of the patent 809212 for short-circuit current limitation in high-frequency generators serving, upstream choke coil arrangement with direct current bias Electrostatic systems connected via a transformer and one or more dry rectifiers Painting and, in the case of electrostatic precipitators, to limit current and / or voltage, in particular No-load voltage limitation and to prevent flashovers.

Fig. 1 shows the basic circuit for current limitation in an electrostatic precipitator. The spray electrode 1 and the Grounded discharge electrodes 2 are connected to the high-voltage transformer 4 via a dry-type rectifier 3 connected. The premagnetized ones used to limit the current and / or voltage are located in its primary circuit Chokes 5 and 6, which are pre-magnetized in opposite directions by a DC winding each will. The bias windings can be fed via a dry rectifier arrangement 7 take place in Graetz circuit. The strength of the bias can be measured at a resistor can be set. An alternating voltage 9 is used to feed the bias circuit and the Main circuit an alternating voltage source 10. In this respect, the basic circuit structure corresponds the main patent.

Despite the current-limiting property of the inductor assembly but can in the event of a short circuit on the high-voltage side of the electrostatic precipitator depending on the type of The core material used for the throttle arrangement may be higher than in normal operation Continuous current arise, the z. B. with normal transformer sheet by about 40 to 50% above the Operating current can be.

The proposal has therefore been made elsewhere to remove the bias circuit from the regulated Main circuit voltage, d. H. from the voltage on the primary winding of the transformer 4 to be fed. When this voltage collapses as a result of a short circuit on the secondary side, the Bias of the chokes to zero or almost zero, so that the continuous short-circuit current to a low value, which can be even lower than the operating current. It is also suggested been added a choke coil 11 in the DC bias circuit insert, which has the task of rapid changes in the bias current counteract and limit the surge short-circuit current.

The invention creates a further possibility for reducing the short-circuit current in the device according to the main patent in that the direct current bias is limited by the rectified difference between current and voltage
in electrostatic painting and electrostatic filter systems

Addition to additional patent 870 874

Applicant:

Siemens-Schuckertwerke

Corporation,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dr. phil. nat. Helmut Dietz,
Dr.-Ing. Walter Hartel and Dr.-Ing. Erich Rolf,

Nuremberg,
have been named as inventors

two alternating currents is formed, one of which is used to set the operating point of the limitation serving premagnetization and the other one that occurs on the working winding of the choke coil arrangement Voltage is proportional and - in the sense of achieving an automatic extinction of a flashover arc - Is dimensioned such that the steady-state short-circuit current is significantly less than the stationary working current.

The circuit and mode of operation are illustrated using an exemplary embodiment shown schematically in FIG described in more detail below. The same reference symbols denote the same parts as in FIG. 1.

According to the invention, the change in the premagnetization is dependent on the voltage drop across the windings of the premagnetized chokes 5 and 6 in the primary circuit. Means an auxiliary transformer connected in parallel to the chokes 5 and 6 17, the voltage drop across these chokes is inserted into the control circuit as a counter voltage. The counter voltage can between rectifier arrangement? and the AC power source 9 is inserted will. It is advantageous to connect to the alternating current source 9 for galvanic isolation to be carried out via an auxiliary transformer 18. at

709 908/340

In normal operation, most of the supply voltage is applied to the high-voltage transformer 4; to the premagnetized Chokes 5 and 6 only provide the counter voltage corresponding to the low inductive voltage drop Tension. In the short-circuit case, however, the voltage at the high-voltage transformer 4 collapses; the supply voltage is then almost in full at the throttles 5 and 6. It can therefore be the counter voltage by appropriate " Choice of the gear ratio of the auxiliary transformer 17 can be made so large that the DC pre-magnetization of the chokes 5, 6 drops to the desired value.

The devices according to the invention are not based on the simple embodiment shown in FIG limited for connection to single-phase power. For example, the transformer 4 can also be three-phase and the associated control circuit be designed accordingly, d. H. instead of the simple series-connected Chokes 5, 6 throttles such series can be provided in a known manner for each phase, so that a three-phase connection results in a choke coil arrangement consisting of six chokes, their bias windings among themselves z. B. can be connected in series. The premagnetization windings the series chokes for each phase must be connected in opposition to one another. The rectifier 3 on the secondary side of the transformer 4 can also be designed in any circuit, for example in a bridge circuit, Greinacher or multiplier circuit. The use of the devices according to the invention is particularly advantageous for current and / or voltage limitation in electrostatic painting and electrostatic filter systems; But it can also be used for any other purpose if the same or similar tasks and conditions are met.

Claims (2)

Patent claims: 1. Device for current and / or voltage limitation in electrostatic painting and Electrostatic precipitator systems, with one on the primary side of the associated high-voltage transformer Choke coil arrangement with direct current bias, according to patent 870 874, characterized in, that the direct current bias is formed by the rectified difference between two alternating currents of which one of the premagnetization serving to set the operating point of the limitation and the other of those occurring on the working winding of the choke coil assembly Voltage is proportional and - in the sense of achieving automatic extinction of a flashover arc - Is dimensioned in such a way that the steady-state short-circuit current is significantly less than that stationary working current. 2. Device according to claim 1, characterized in that to produce the same relative conditions at different normal currents the voltages proportional to these and the bias voltage are removed via auxiliary transformers, which are designed as regulating transformers and are coupled to each other. Considered publications:
German Patent No. 824812;
VDE technical reports 1951, p. 143, p. 147;
ETZ 1937, p. 990 ff .; 1952, p. 205. 1 sheet of drawings © 709 908/340 2.58