DD229547A1 - PROTECTION CIRCUIT FOR A HIGH VOLTAGE CHECK - Google Patents

Abstract

The invention relates to a protective circuit arrangement for a high voltage test system, which consists of at least one actuator and a Prueftransformator, wherein the Primaerwicklung the Prueftransformatoren an electronic circuit breaker is connected in parallel and the circuit breaker of a control stage is switched on, depending on the turnaround of a Prueflings a Signal is received. It is an object of the invention to provide a protective circuit arrangement by which the test system is safely protected, but no reduction of the available net power occurs by components. This object is achieved according to the invention in that between the control unit and connection point of the circuit breaker and primary winding, a further circuit breaker is provided, which opens in time approximately with the closing of the circuit breaker.

Description

Protective circuit arrangement for a high voltage test system

Field of application of the invention

The invention relates to a protective circuit arrangement for a high-voltage test system, which consists of at least one actuator and a test transformer, wherein the primary winding of the test transformer, an electronic circuit breaker is connected in parallel and the circuit breaker of a control stage is switched on, depending on the penetration or impact of a test specimen receives a signal.

Characteristic of known technical solutions It is known to protect high-voltage test transformers against overvoltages resulting from voltage breakdowns on a test object by means of an overvoltage protection device arranged at the input terminals of the test transformer. These impermissibly high recovery voltages occurring at test specimen flashovers or breakdowns can increase up to twice the nominal value of the test voltage. The overvoltage protection device can now be realized with various means. Thus, a triggerable spark gap can be connected in parallel to the primary winding of the test transformer, which receives an ignition pulse as a function of Obei- or breakdown of the specimen (DE-AS 22 11 985). Furthermore, it is known to lay a fast S _c holder, such as a thyristor switch, parallel to the primary winding of the test transformer (Train: Prevention of

TuR file 1.890 - 2 -

recovery overvoltages on high voltage testing transformers, IEEE Trans. Power App. and Syst. 92 (1973) 5, pp. 1531-1641). In the event of a flashover or overflow on the test specimen, the switch is closed, thus protecting the test transformer from damaging high voltages. The ignition pulses for the thyristor switch are given by a control unit which is in communication with a voltage indicator connected in the test circuit.

However, since the thyristor switch in terms of performance strongly stressed the upstream actuator in power, it is necessary to switch inductive or ohmic attenuators in the cable between the actuator and connection point of the thyristor and primary winding of the test transformer. It is disadvantageous that due to the voltage drop across the attenuators, the output voltage of the test system decreases more with increasing load by the P _r üfling, so that the available useful power is reduced in steady operation.

Object of the invention

The invention aims to avoid the stated disadvantages.

Explanation of the essence of the invention

The invention has for its object to provide a protective circuit arrangement of the type mentioned that protects both test transformer and DUT from surges and the actuator from overload safely and in which the available power is not reduced by components of the protection circuit.

This object is achieved by the characterizing part of claim 1. Advantageous embodiments are subject matter of claims 2 to 4.

embodiment

With reference to a drawing, the invention will be described in more detail below

TuR file 1890 - 3 -

be explained. In the drawing, a protective circuit arrangement for a high voltage test system is shown, which consists of a variable transformer 1 and a Hochspannungsprüf transformer 2. The variable transformer 1 is connected on the secondary side to the primary winding 3 of the test transformer 2. The test transformer 2 operates on the secondary side to a test object 4. To protect the test transformer 2 and DUT 4 against excessive high V / iederkehrspannungen the primary winding 3 a thyristor 5 is parallel connected in parallel. In order not to overload the variable transformer 1 in the case of the response of the thyristor 5, another thyristor S between the variable transformer 1 and the connection point of the primary winding 3 and thyristor 5 is switched. In power-weak systems, the other thyristor 6 can be replaced by a circuit breaker. The thyristor 5 and 6 are controlled by a control stage 7, which communicates with a switched into the ground line of the specimen 4 indicator 8. By this indicator 8, the control stage 7 is informed of occurring through or overturning and the control stage 7 outputs switching signals to close the thyristor 5 and to open the other thyristor switch 6 from.

To avoid voltage overshoots when switching on the high-voltage test system, the control stage 7 may be connected to a stage 9 for the formation of voltage zero signals and be further formed so that the switching of the system follows by the other thyristor switch. The stage 9 is connected on the input side to the supply voltage of the variable transformer 1.

The protective circuit arrangement can also be developed as a monitoring device against 'high voltage and overcurrent in case of accident or incorrect operation. For this purpose, the control stage 7 current and voltage value signals are supplied, for example, from one in the primary circuit of Prüftrans-

Tu.1-file 1890 - 4 -

Formators2 switched current transformer 10 and of a tap 11 of the high-voltage winding of the test transformer.

In this embodiment, the indicator 8 in .Vegfall and the signaling of Prüflingsüber- or, durchdurch from the tap 11 are taken over.

When exceeding vorwählbarsr thresholds issued the control stage 7 switching signals to the other thyristor switch 6 so that the call system is protected against overcurrent or overvoltage by opening this thyristor.

Claims (4)

TuR file 1890 claims 1. Protective circuit arrangement for a high-voltage test system, which consists of at least one actuator and a test transformer, wherein the primary winding of the test transformer, an electronic circuit breaker is connected in parallel and this circuit breaker is switched by a control stage, which receives a signal depending on the through or top of a DUT , ·· characterized in that between the control unit (1) and the connection point of test transformer (2), circuit breaker (5) and control unit (1), a further circuit breaker (5) is provided, which is about the time of closing the circuit breaker (5) opens 2. Protection circuit arrangement according to claim I _1, characterized in that the further power switch (5) is designed with two antiparallel-connected thyristors, which are in communication with the control stage (7) and with respect to the circuit breaker (5) receive inverse switching signals. 3. Protection circuit arrangement according to claim 2, characterized in that the control stage (7) is connected to a stage (9) for the formation of voltage zero point signals, which is connected on the input side to the supply voltage for the control unit (1), and in that the control stage (7 ) to the other thyristor switch (6) are turn-on signals only at the time of voltage zero crossings. 4. Protection circuit arrangement according to claim 2, characterized in that the control stage (7) from the primary circuit of the test transformer (3) removed current value signals and the secondary circuit removed voltage value signals are supplied and the control stage (7) when exceeding pre-selectable limits for current and voltage switching signals to the another circuit breaker (6). For this 1 sheet drawing