DD76737B1 - HIGH VOLTAGE GENERATOR FOR GENERATING CAVED PERIODIC TEST VOLTAGES (SWITCH VOLTAGES) - Google Patents

Description

Characteristic of the known technical solutions

Such a test transformer is by the journal ETZ-A, Bd. 81, H. 10 v. 09/05/1980. Pages 355 to 360, known. There is a need to make the feeding of the discharge even at such low-voltage windings, which are not operationally at ground potential. This is z. B. necessary if two transformers are operated in series and the earth potential closest to the winding with an AC voltage z. B. mains frequency is fed. In addition, there is a need for providing multiple excitation voltage generators feeding different low-voltage windings for the purpose of enabling a large frequency of test voltage. Under such conditions, the switching voltage excitation voltage generator must be located at the potential that the winding assumes during the switching voltage test, which is conveniently done so that the excitation voltage generator is incorporated into the test equipment. However, then there arises the problem of charging the excitation voltage generator, because the excitation voltage generator must be isolated from the supply voltage source against this potential difference.

To solve this problem, it makes sense to charge the exciter voltage generators via isolation transformers. It has also been considered to charge the exciter voltage generators from ground potential and to disconnect the exciter voltage generator from the ground potential by means of a switch after completion of the charging, which isolates in the open state against the potential differences that occur. Both solutions are extremely expensive.

Object of the invention

It is purpose of the invention to avoid the described disadvantages of the previously known solution.

Explanation of the essence of the invention

The invention is based on the object, without the use of expensive means the charging of exciter voltage generators, which are arranged at different potential of a test transformer or a Prüftransformatorkaskade

 This object is achieved according to the invention by the totality of the following features:

a) the test transformer is fed via an on or near ground potential excitation winding with AC voltage.

b) the capacitor is supplied via the low-voltage winding of the test transformer used for the discharge,

c) switches are provided which connect the excitation winding with an AC voltage source and the rectifier with the low-voltage winding of the test transformer for charging the capacitor,

d) the test transformer has to generate the test voltage on multiple chargeable capacitors, each of which is associated with a lying at the same potential low-voltage winding.

A further development of the invention is that the test transformer forms a cascade with at least one further Prüftransforntator, each of the further test transformers is fed via an excitation winding which is connected to a coupling winding of the next lower stage, and wherein each further test transformer own, on corresponding potential lying test voltage generation (exciter voltage generator) has. Developments of the invention further consist in that the trigger signal for discharging the capacitors is derived from the turn-off of the AC voltage, and that in the cascade, the terminals of the exciter winding of the uppermost transformer and the over-winding of the lowermost transformer are interchangeable, so that when energized the same by AC voltage to charge the capacitors, the voltages of the high voltage winding compensate, while adding up when discharged.

embodiment

Reference to an embodiment of the subject invention is explained, starting from a two-stage cascade.

Both transformers each consist of a two-core core 1. On each of the legs, both a thrust winding 2 and a high-voltage winding 3 is arranged, wherein the high-voltage windings are connected in series. In addition, each carries a leg of a transformer, a field winding 4 and the other leg of the transformer a coupling winding 5. To achieve higher frequencies in the switching voltage generation two exciter voltage generators 6 are provided, each working on the parallel-connected thrust windings 2. They are also located at the potential that the thrust windings assume during operation. In order to enable the charging of the capacitor battery containing in the excitation voltage generators 6, the test transformer cascade is applied to AC voltage via a switch 7 and thus excited.

A switch 8 between the thrust windings 2 and the exciter voltage generators 6 is connected so that the voltage induced in the thrust windings passes through the rectifier provided in the exciting voltage generator to the capacitor bank of the exciting voltage generator. After charging the switch 7 is opened and the switch 8 folded. Via a control unit 9 then takes place the initiation of the discharge of the exciter voltage generator via the thrust winding 2 and thus the generation of the switching voltage. The excitation voltage for the winding 4 is chosen so that there is an AC voltage at the output of the high voltage cascade; which is insignificant for the examinee. If you want to avoid a load of the specimen with AC voltage completely, so it is in addition to the known measures, eg. Example, also possible during the charging process, the connections of excitation winding 4 of the uppermost transformer and the coupling winding 5 of the lowermost transformer to swap, causing a compensation of the voltages induced in the high-voltage windings 3.

Documents considered:

DE-PS 340645 (21 d 2, 49)

DE-PS 340647 (21 d 2.49)

DE-PS 368474 (21 d 2, 49)

GB-PS 1130644 (H 03 K, 1/00)

ETZ-A, H. 10.1960, p.355-360

Isvestiya NHH Postojamogo Тока 1961,8, p. 367/389

-з-

96Ψ3Ψ

Claims (4)

A high-voltage generator for generating attenuated periodic test voltages (switching voltages) using a test transformer and a capacitor which can be charged with AC voltage via a rectifier, which can be discharged to generate the test voltage via a low-voltage winding of the test transformer, characterized by the following features: a) the test transformer is fed via an on or near ground potential lying excitation winding with AC voltage, b) the capacitor is supplied via the low-voltage winding of the test transformer used for the discharge, c) switches are provided which connect the excitation winding with an AC voltage source and the rectifier with the low-voltage winding of the test transformer for charging the capacitor, d) the test transformer has to generate the test voltage on multiple chargeable capacitors, each of which is associated with a lying at the same potential low-voltage winding. 2. High voltage generator according to claim 1, characterized in that the test transformer forms a cascade with at least one further test transformer, wherein each of the further test transformers is fed via a field winding, which is connected to a coupling winding of the next lower stage, and wherein each further test transformer a own test voltage generation (excitation voltage generator) lying at the corresponding potential. 3. High-voltage generator according to claim 1, characterized in that the trigger signal for discharging the capacitors is derived from the turn-off operation of the AC voltage. 4. High-voltage generator according to claim 1, characterized in that in the cascade, the terminals of the excitation winding of the lowermost transformer are mutually interchangeable, such that when energized the same by AC voltage to charge the capacitors to compensate for the voltages of the high-voltage windings, while they discharge add. For this 1 page drawing Field of application of the invention The invention relates to a high voltage generator for generating attenuated periodic Prüfspannungen {switching voltages) using a test transformer and an AC voltage with a rectifier charging ble capacitor, which is dischargeable to generate the test voltage via a low-voltage winding of the test transformer.