Fault voltage circuit breaker

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The earth leakage circuit breaker , as FU switch or English Earth Leakage Circuit Breaker - ELCB called, is a protective device in the low-voltage network that is no longer used in Germany today and by the residual-current device was replaced (RCD, RCD).

FU switch

History

The frequency converter circuit breaker was produced well into the 1950s. It was not until 1958 that the residual current circuit breaker with the FI circuit breaker was listed for the first time as a protective measure in the VDE regulations . In the meantime, the residual current protective circuit has completely replaced the residual voltage protective circuit.

Switching a frequency converter

In a TT network with a grounded neutral point of the transformer and separate grounding on the consumer network, it is often very difficult to achieve the low grounding resistance that is necessary to trigger the upstream fuses in the event of a fault . In the early days of the electrical energy supply, there were repeated electrical accidents in which people also died.

Otto Heinisch published first thoughts on this problem in the Elektrotechnische Zeitschrift (ETZ) as early as 1914 under the title "Safety circuit for damp rooms". Heinisch was operations director in the Wesel administration of the RWE . Together with Anton Riedl, head of the Kleve operations department at RWE, the Heinisch-Riedl fault voltage circuit breaker was developed in the following years and patented by the RWE operations administration in Wesel . The license to build the switch was given to several companies. The first fault voltage (FU) circuit breaker was presented to the public at the Leipzig trade fair in 1924. In the same year, the first fault voltage protection circuit was installed in Louisendorf (west of Kalkar ).

Layout and function

The earth leakage circuit breaker measures the voltage at the ground of the system, in the adjacent plant this is the terminal K , and used as a reference an auxiliary earth electrode, in the circuit diagram of the terminal e . All metal parts to be protected in the house need to the ground point K are connected. For this purpose, an additional wire is required for the electrical installation, the protective conductor . The auxiliary earth electrode at connection E must be at least ten meters as the crow flies from the earth electrodes of the system, which is often problematic in densely built-up areas. At voltages above 24 V, the coil S and the key switch are switched off. The current flowing through the coil S is about 45 mA.

In the Heinisch-Riedl fault voltage protection switch, also known colloquially as "Trennwart", the fault voltage coil was together with a thermal overcurrent release, a test button with test resistor R , an overvoltage protection system and a four-pole main switch (for the three outer conductors L1 , L2 and L3 and the neutral conductor N ) built into a housing.

Laws and norms

  • IEC 364-4-1 / VDE 0100 Part 410 Protective device and switch-off conditions
  • IEC 364-3 / VDE 0100 part 310 Protective measure against indirect contact with shutdown or message
  • IEC 364-4-41 / VDE 0100 Part 410 Protection against electric shock

See also

literature

  • Günter Springer: Expertise in electrical engineering. 18th edition, Verlag - Europa - Lehrmittel, 1989, ISBN 3-8085-3018-9
  • A. Senner: Electrical engineering. 4th edition. Verlag - Europa - Lehrmittel, 1965

Individual evidence

  1. ↑ DIN VDE 0100-410: 2007-06 (IEC 60364-4-41: 2005) Section 411.4.5 using the example of the TN system (as for the other systems) only overcurrent protective devices and residual current protective devices are listed as permissible.
  2. ↑ G. Biegelmeier, G. Kiefer, KH Krefter: Protection in electrical systems, Volume 5, SR84 . VDE-Verlag, 1999, ISBN 978-3-8007-2052-1 ( online ).

Web links