Earth leakage circuit breaker
The error voltage circuit breakers, also known as FU switch or English Earth Leakage Circuit Breaker - called ELCB, is a protective device in the low voltage network, which is no longer used today in Germany and was replaced by the residual current circuit breaker ( RCD, GFCI ).
History
The FU - breaker was produced in the 50 years inside. Only in 1958, the fault current protection circuit was performed with the GFCI as a protective measure for the first time in the VDE Specifications. Meanwhile, the fault current protection circuit has the fault voltage protection circuit completely replaced.
Design and function
In a TT- system with earthed neutral point of the transformer and separate grounding on the power consumption, it is often very difficult to achieve the low ground resistances that are necessary to trigger the upstream fuses in case of error.
Therefore, in the early days of electric power supply, it always came back to power accidents in which people also were killed. Under the title " safety circuit for damp rooms " Otto Heinisch published already in 1914 first considerations about this problem in the Electrotechnical Journal (ETC). Heinisch was Director of Operations in the operations management of RWE Wesel. Together with Anton Riedl, head of the operations department of RWE Kleve, the Heinisch- Riedl error voltage circuit breaker has been developed and patented by the RWE operations management Wesel in the following years. The license for the construction of the switch has been awarded to several companies. At the Leipzig trade fair for the first error voltage ( FU) public safety switch was introduced in 1924. In the same year, the first error voltage protection circuit in Louis village (west of Kalkar ) was installed.
The error voltage circuit breaker measures the voltage at the grounding point of the system, in the adjacent plant, this is the terminal K, and used as a reference an auxiliary earth, in the circuit diagram of the terminal E. All must be connected to the grounding point K to be protected metallic parts in the house. For this purpose, in the electrical installation an additional wire is required, the protective conductor. The auxiliary earth at terminal E must be at least ten meters in a straight line to be removed from the earth electrodes of the system, which is often problematic in built-up areas. At voltages above 24 V is switched off via the coil and the switch S lock. The current thereby flowing through the coil S, is about 45 mA.
When Heinisch- Riedl error voltage circuit breaker, colloquially referred to as " separation Waiting ", the error voltage coil was with a thermal overcurrent trip, a test button to test resistor R, a surge protector ÜS and a four-pole main switch ( for the three phases L1, L2 and L3 and the neutral conductor N) installed in a housing.
Laws and standards
- 364-4-1/VDE IEC 0100 Part 410 safety guard and shutdown conditions
- 364-3/VDE IEC 0100 Part 310 Protection against indirect contact by means of disconnection or message
- 364-4-41/VDE IEC 0100 Part 410 Protection against electric shock