DD139469A1 - METHOD AND CIRCUIT ARRANGEMENT FOR ELECTRICALLY TESTING THE PLASTIC PANELS OR THE PLASTER HOLES OF POWER CABLES - Google Patents

Abstract

The invention relates to a method and a Schaitungsanordnung for electrical testing of plastic sheaths or plastic protective sheaths of Power cables. The aim of the invention is to provide a method and a Schaitungsanordnung 'for electrical testing of the plastic shells or, To develop plastic protective covers of power cables to those in the required test methods. Switching operations and one Reduce supply reliability. Erfindungsgeraäß. ., the protective conductor of the power cable is isolated from the area endangered by the operating voltage hejj carried out and detachably connected to a grounding system. For 'checking' the will Protective earth conductor separated on all sides from the grounding systems and via a Safety device · 'the measuring and testing device closed,. This method and this "arrangement" are suitable for testing the 'Plästmäntal' or plastic protective covers of Ein- and Three-wire power cables.

Description

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Method and circuit arrangement for electrical testing of plastic sheaths or plastic protective sheaths of power cables

The invention relates to a method and a circuit arrangement for the electrical testing of plastic sheaths or plastic sheaths of power cables

Characteristics of the known technical solutions

Known are methods and circuit arrangements for electrical testing of plastic sheaths or "plastic sheaths of voltage-free power cables * The electrical testing is carried out with the aid of a Prentspannung» The known tests require the shutdown of the test to be tested = power cable, so that a reduction in the supply reliability arises a supply failure can be caused.

Aim of the marriage _,

The aim of the invention is to provide a method and a circuit arrangement for the electrical testing of the plastic shells or plastic protective sheaths of power cables . to avoid the switching operations required by the known test methods and the reduction of the reliability of the supply and the possible supply failures «

The invention is based on the object, a method and a circuit arrangement for electrical testing of Plastmän

te! or plastic sleeves of operating power cables to create. According to the invention, this object is achieved in that the protective conductor of the "high-current" cable to be tested is led out of the area which is endangered by the operating voltage and connected to a grounding system To shut down the power cable, a safety device connected between the protective conductor and the effective grounding system and connected to a measuring device and the connections between the protective conductor rind the grounding systems open on all sides.

The safety device, which is intended to prevent a hazard to the tester and the test equipment in the event of a fault of the power cable during the test specimen, consists of a protective spark gap, a switch between the insulated protection idter and the grounding system and a fuse. Via two terminals of the safety device either the measuring device can be connected directly or via a rectifier set or via a transformer-Gl-eichrichter combination or a combination of resistors under supply of a foreign voltage. The test or measurement can be carried out using a known voltmeter or a combination of known current and voltage meters or "oscillographs." The interposition of the various circuit elements between the safety device and the device allows various measurements and tests. Thus, the interposition of a rectifier enables the measurement of the height and / or curve shape of a half-wave of the alternating voltage applied to the protective conductor,

The interposition of a transformer-rectifier combination allows the same measurement when the applied AC voltage is relatively small. The measurement can also be carried out using a different test voltage, the required alternating voltage being reduced by a combination of resistors to a value insignificant for the test result, if necessary.

The invention will be described below with reference to an exemplary embodiment.

In the drawing mean:

Fig; 1 power cable with connected safety device and measuring device

Fig. 2 rectifier and measuring device ^:

Figo 3 transformer-rectifier combination and measuring device

Fig. 4 resistance combination with measuring device and external voltage sζufuhrung

The test on the power cable in operation is carried out in such a way that the protective conductor 1 of the power cable is led out of the area exposed by the operating voltage and detachably connected to the grounding system 2. For testing, these connections are opened on all sides and, as shown in FIG. 1, the protective conductor 1 and the Er-. The safety device 3 consists of a protective spark gap, a switch and a fuse. · In case of an inadmissible voltage between the protective conductor 1 and the earthing system 2, the protective conductor 1 should be earthed through the protective spark gap and the switch. The fuse prevents an inadmissible Strorafluß on the circuit arrangement for Hesseinrichtung 4 "About two..Anschlußklemmen a, b at the safety device can either the measuring device 4 for testing the plastic blanket or, the plastic protective cover 5 directly or-, as in that Fig. 4 or 4, via the rectifier 6 or a transformer-rectifier combination 7 or a combination of resistors 8 while supplying an external voltage E 2. The measuring device 4 may optionally consist of a voltmeter or a combination of voltage and current meters or * an oscilloscope »'The circuit arrangement shown in Figure _s 2, serves to measure a half-cell of the present on the protective conductor 1 AC voltage E- · while the circuit arrangement shown in Fig * 3 with the test

the transformed and equal-rectified AC voltage Ξ-j present on the protective conductor 1 permits. 4 circuit arrangement allows a test of the plastic casing or, the plastic protective cover with a foreign DC, AC or surge voltage Ξ2. If necessary, the pending AC voltage E-i is reduced to a value insignificant for the test result by a combination of resistors $.

Claims (4)

claim 1 * Method and circuit arrangement for electrical testing of Plastinäntel and Plast Schutzhüll s of power cables, characterized in that the test carried out on the power cables in operation and that 'their protective conductor (1) led out of the endangered by the operating voltage range and with the Grounding systems (2) detachably connected v / earth, said connections open for testing on all sides, the protective conductor (1) via a safety device (3) optionally connected to the measuring device (4) and the examination of the Plastmantels or Plastschutzhülle- (5) by means of the on the protective conductor (1) pending AC voltage (Bj) or a foreign Gleich ™, AC or surge voltage E2 is made *. 2 * Method and circuit arrangement according to item 1, characterized in that the height and / or the curve shape of the alternating voltage (Ξ-j) present on the protective conductor (1) is measured directly or with the use of a rectifier (6) 3 "method and circuit arrangement according to the points 1 and 2, .gekennzeichnet characterized in that in the transformer-rectifier combination (7) transformed and rectified, on the protective conductor (1) pending AC voltage (E-]) is checked. '. 4 »method and circuit arrangement according to the points 1, 2 and 3, characterized in that on the protective conductor (1) pending. AC voltage (E-j) if necessary by a combination of resistors- (8). is reduced and tested with a foreign DC, AC or surge voltage (Ξ2). Hiexsu Ί page drawings,