DD276166A1 - CONTACTLESS ARRANGEMENT FOR CHECKING PROTECTIVE EQUIPMENT ELECTRIC HOUSEHOLDERS WITH HEAT RESISTANCE - Google Patents

Abstract

The invention relates to an arrangement for testing earth-proof household electrical appliances with heating resistor in the semiconductor switches (thyristors, triacs) can be used without problems and in which the Schutzleiterpruefung temporally parallel to Ableitstrom-, high voltage and Funktionspruefung expires. The operating voltage for the test is disconnected from the mains via a transformer, the secondary circuit is connected to one terminal of the series connection of the secondary windings of at least two transformers and the other terminal is connected to a grounded measuring resistor for the evaluation of the leakage current and high voltage test. The transformers are switched on the primary side via semiconductor switches. figure

Description

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Field of application of the invention

The invention finds application in the electrical appliance industry in the testing of the protective conductor connection, the working current, the high voltage resistance and the current consumption of electrical household appliances with heating resistance, such as grills, irons and similar devices.

Characteristic of the known state of the art Frequently, a classic test set-up, consisting of a PE conductor test device, is used to test the electrical parameters. High voltage tester and voltmeter and ammeter used. To automate the test procedure, these devices

installed in a control cabinet and the corresponding voltages and currents with the help of a controller via contactors or relays led to the DUT and the various evaluation.

From the catalog of the VEB Kombinat Elektrogerätewerk Suhl is an automatic testing device for electrical Final inspection of irons has become known, which includes a control with contactors and relays. The known technical solutions, even if they are effective in an automatic device, have the disadvantage

that they are susceptible to interference by the use of electrical contacts and with a high maintenance and cause a significant noise level.

Furthermore, the individual tests are successively felt in the known technical solutions, so that a

high expenditure of time is required and often several testers must be operated.

Object of the invention

The object of the invention is to develop a contactless device for testing electrical equipment with heating resistor, which is characterized by störunar.fällige and noiseless operation, parallel to the Schutzlßiterprüfung performs the other tests and requires low weight and small footprint.

Explanation of the essence of the invention

The invention has the task of providing a circuit arrangement m which the problem lost use of H * albleitersch (ILTERN, preferably thyristors or triacs, makes possible and in which the Schut? Pus parallel testing may proceed with other tests.

The use of triacs instead of electrical contacts in conventional circuits is not without problems because of the high voltages. A series connection of triacs or thyristors requires the equalization of the blocking voltages by parallel connection of capacitor-resistor combinations and therefore has a disturbing reverse current result. The usual way of switching, dia voltage sources for the leakage current and the high voltage test einsaitig to ground potential uod to measure the leakage current with an instrument or a measuring resistor between the device housing and earth and grounding the protective contact or the DUT in the PE test, allows a parallel operation of the protective conductor test to the first two tests.

According to the invention, both the problem of high-voltage strength and the problem of Parallelpnifung be solved by the operating voltage for the test under a transformer disconnected from the mains, its secondary winding by two series-connected secondary windings of two other transformers in the case of leakage current test at test voltage potential or in the case of High-voltage test is placed on Hochspannungspotemial, a common measuring resistor for the leakage current and high-voltage test from the other end of the series-connected secondary windings switched to ground and all transformers are connected on the primary side via triacs. In order to avoid inrush surges, the ignition of the triacs must be carried out in the voltage maximum, which is easy to implement because of the agility of the semiconductor switch gogenüber relay or contactors via an electronic control. As blocking voltage for the triacs occurs at most the mains peak voltage.

An essential feature of this arrangement is that no connection of the test lungs dura the test must be switched directly with a contact or triac. Also, the connection of the operating voltage is easily possible, so that even the functional test can be done in parallel to Schutzlciterprüfung. The device housing is grounded together with the PE test voltage. The voltage drop across the measuring resistor for the leakage current test and the high-voltage test and the voltage drop between the protective contact and the housing of the DUT are thus at common ground potential, allowing for unproblematic evaluation of the signals.

embodiment The invention is explained in more detail below using an exemplary embodiment. The arrangement is at the terminals 1 and 2

powered by the grid. At the beginning of the test Triac 3 and 4 are fired simultaneously. The transformer B generates the

Protective earth test current, the intact Schuuleiteranschluß via the protective contact 6 and the ground terminal 7 of the DUT. 8

flows. The evaluation circuit 9 detects the voltage across the protective conductor connection as an error criterion.

At the same time from the transformer 10 via the secondary winding of the non-switched transformer 11, the test voltage for Leakage to the terminal 12 of the DUT 8 logged. The caused by the Abtritttrcm on the heating resistor 13 Voltage drop did negligible, so that at the terminal 14, the same potential as the terminal 13 is located. The Arbeitoetrom flows back to the transformer 10 via the ground terminal 7 and the measuring resistor 15. The voltage drop at the Measuring resistor 15 is fed to the evaluation circuit 16 as an error criterion. After elimination of the test time for the leakage current Triac 17 is additionally ignited. Now lies at the terminal 12, the high voltage, the

is the sum of the secondary voltages of transformers 10 and 11. In the case of a high-tide overflow, the

Current as in the leakage current test on the measuring resistor ' 5, the voltage drop in this test phase as Criterion of the evaluation. After expiry of the test time for the high-voltage test Triac 4 and 17 go out, but Triac 18 is ignited and feeds over

the transformer 19den heating resistor 13. The heating current is electrically isolated with the current transformer 20 and the resistor 21 into a ground-related voltage drop and fed to the evaluation circuit 22.

Until the end of the entire test, the protective conductor test runs in parallel with the other tests, without any mutual interference Influencing takes place.

Claims (3)

1. Contactless arrangement for testing earth-proof domestic appliances with heating resistor, characterized in that the Prüflingsanschlüsse (12; 14) by an isolating transformer (1S) are fed, the secondary winding on one side with a terminal of the series connection of the secondary windings of at least two transformers (10; 11) and the other terminal is connected to a grounded sense resistor (15). 2. Arrangement according to claim 1, characterized in that the transformers (10; 11; 19) are switched on the primary side via semiconductor switches (4; 17; 18). 3. Arrangement according to claim 1 and 2, characterized in that in an automated sequence, the protective conductor test abll jagt in time parallel to the other tests.