EP0113025B1 - Earth leakage circuit breaker - Google Patents

Abstract

1. The use of an earth leakage circuit breaker having arranged in the secondary circuit of a sum current transformer (3), whose primary winding has a number of turns that is adequate at 50 Hz, a magnetic blocking device (4) as a frequency-independent earth leakage circuit breaker in a frequency band from about 16 2/3 Hz to 400 Hz.

Description

The invention relates to the use of a residual current circuit breaker.

Residual current circuit breakers, which are equipped with a tripping device common today, work with a holding magnet and are set to an operating frequency of 50 Hz. If such residual current circuit breakers are to protect consumers in networks with a different frequency, the frequency dependency of the holding magnet system interferes. Standard holding magnets are most sensitive at 50 Hz and since their tripping range increases to lower tripping currents at lower frequencies and especially at higher frequencies, special precautions are necessary to ensure tripping at required values.

With a conventional holding magnet system, only residual current circuit breakers for use up to a maximum of 400 Hz at nominal currents of 25 A for nominal residual currents of 30 mA could be implemented through targeted measures in individual cases. In order to upgrade a residual current circuit breaker for operating frequencies that deviate from the usual 50 Hz, the number of primary windings has been increased. In addition, the test circuit with which the operational capability of the residual current circuit breaker can be tested had to be specially made or set. Such measures result in a special type of residual current circuit breaker with holding magnet for a narrow frequency range that deviates from the usual 50 Hz.

Residual current circuit breakers that work with a tripping device designed as a blocking magnet were used in earlier years (Siemens-Zeitschrift, 1960, pp. 229 to 231). Such residual current circuit breakers have only been used in the usual frequency range of 50 Hz.

The invention has for its object to provide a residual current circuit breaker which is frequency-independent in the frequency range of the technically used frequencies, which in other words can trigger safely at these frequencies without changes in adaptation and protect consumers.

The solution to the described problem is according to the invention in the use of a residual current circuit breaker, in the secondary circuit of a summation current transformer with a sufficient number of primary windings at 50 Hz, a blocking magnet device is arranged, as a frequency-independent residual current circuit breaker in a frequency range of about 16 2/3 Hz to 400 Hz.

Such a residual current circuit breaker triggers reliably with alternating residual currents up to frequencies of about 400 Hz.

The residual current circuit breaker can also detect residual currents with DC components. For this purpose, the summation current transformer can be manufactured in a manner known per se (DE-B-20 44 302) from a core material with an F characteristic. Ultraperm 80 ^m from Vacuumschmelze, for example, is suitable for this.

• In Fig. 1 ist ein frequenzunabhängiger Fehlerstromschutzschalter mit einer Sperrmagnetvorrichtung veranschaulicht. In Fig. 2 ist ein frequenzunabhängiger Fehlerstromschutzschalter nach Fig. 1 wiedergegeben, der zugleich auch Fehlerströme mit Gleichstromkomponenten erfassen kann. In Fig. 3 ist ein anderes Ausführungsbeispiel für einen Fehlerstromschutzschalter wiedergegeben, der mit einer Sperrmagnetvorrichtung arbeitet und im Sekundärkreis einen Kondensator in Parallelschaltung aufweist, um nicht nur Wechselstrom-Fehlerströme sondern auch Fehlerströme mit Gleichstromkomponenten erfassen zu können.

The invention will now be explained in greater detail on the basis of exemplary embodiments shown roughly schematically in the drawing:

• 1 shows a frequency-independent residual current circuit breaker with a blocking magnet device. FIG. 2 shows a frequency-independent residual current circuit breaker according to FIG. 1, which at the same time can also detect residual currents with direct current components. FIG. 3 shows another exemplary embodiment of a residual current circuit breaker which works with a blocking magnet device and has a capacitor connected in parallel in the secondary circuit in order to be able to detect not only AC residual currents but also residual currents with direct current components.

1 monitors conductors 1 and 2, which are routed through primary current transformer 3 as primary windings. A triggering device 4 with a blocking magnet is arranged in the secondary circuit of the summation current transformer. It is in operative connection with a switch lock 5, which can open the switch contacts 6.

In the exemplary embodiment according to FIG. 2, a capacitor 7 is connected in a row arrangement in the secondary circuit of the summation current transformer 3. It is tuned to the frequency of the voltage at least approximately to resonance, which induces a fault current containing direct current components flowing in the primary circuit on the secondary side of the summation current transformer 3. In the exemplary embodiment according to FIG. 3, the capacitor 7 according to FIG. 2 is switched on in a parallel arrangement in the secondary circuit.

Such residual current circuit breakers respond not only to AC residual currents but also to those residual currents which contain DC components in which conventional residual current circuit breakers cannot respond.

The residual current circuit breakers according to FIGS. 1 to 3 also have the advantage that they trip reliably as long as residual currents pose a risk to the consumer, since they are network-independent for their operation. Other known electronic residual current circuit breakers, on the other hand, require an intact network in order to be able to work. B. a multi-conductor network is partially disturbed or interrupted, but a fault current still can flow. Residual current circuit breakers of this type do not require a test circuit that is specially matched to the operating frequency when using approximately 16 2/3 Hz to 400 Hz. Residual current circuit breakers of this type with a blocking magnet and, moreover, the training that is customary today for use at 50 Hz are therefore suitable for an application range from approximately 16 2/3 Hz to beyond that for the frequency of up to 400 Hz that occurs in common technical networks.

Claims (1)

1. The use of an earth leakage circuit breaker having arranged in the secondary circuit of a sum current transformer (3), whose primary winding has a number of turns that is adequate at 50 Hz, a magnetic blocking device (4) as a frequency- independent earth leakage circuit breaker in a frequency band from about 16 2/3 Hz to 400 Hz.

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