DE1809025C - Protective circuit for portable consumer units connected to earthed networks - Google Patents

Description

The invention relates to a protective circuit with a short response line for earthed networks connected portable appliances with a protective conductor to which a residual current circuit breaker is connected upstream with a specified nominal error »irom below 5DmA, at which the Protective conductor is routed through at least one switching contact of the residual current circuit breaker and to one or several series-connected primary windings of the summation current transformer of the circuit breaker, the total number of turns; ihl at least double!, see above as large as the number of turns of one of the primary windings for the connection of an outconductor or the neutral conductor is connected. according to the Hatipt patent 17 63 584.

With this protective circuit according to your I Inuplputeiit can be achieved if, for example, a residual current circuit breaker with a nominal additional current is used of 30 inA used that:

1. In the event of a body contact with the device, the switch if the Fchler current exceeds 30 mA, 6 ;;

2. in the case of a live protective conductor of the socket and thus a live Device housing when touched by an earthed person the switch switches off at a current below 15 mA,

3. a neutral conductor used as a protective conductor in the system remains fully effective as long as it is OK is and

4. If the protective conductor is interrupted and the device is simultaneously connected to the body when it is touched through a grounded person the switch stands like in case 1 with one Current over 30 mA switches off.

However, this high-quality protective measure also has an operational disadvantage: the neutral conductor and thus a protective conductor connected to it almost always carry a low, harmless voltage geeen earth. Come! now with the proposed protective circuit the metal housing of a connected Electrical device, for example a protective hand drill, with a good earth in Touch, this low neutral voltage is sufficient to allow a current to flow to earth. which exceeds 15 mA and thus activates the fault current release, which is not necessary in this case would.

The task of this disadvantage at the entrance to avoid described high-quality protective circuit ■■> - is achieved according to the invention in that in Jem residual current circuit breaker in the Stromkrc eic protective conductor < in series a voltage dependent. Resistance connected to a characteristic i> .. according to which the resistance is high at low voltages, but very low at higher voltages Ut. According to one embodiment, this span length-dependent resistance is simply made up of two equal, oppositely directed zener diodes switched in series, to those in Reiiv a limiting resistor is kept.

The small Nu! - Line voltage blocked in both half-waves. Duk '> the electrical resistance becomes the current durui the diodes at full mains voltage, for example a breakdown Jer isolation of the connected F 'electrical device, limited to a maximum value.

F. it is possible to use the. circuit according to the invention with the residual current circuit breaker in a plug to be installed, the one on the mains side as a - preferably two-pole - Warii plug with protective conductor contacts is formed, and in those on the consumer side a movable device connection line is introduced. 7u the benefit of preventing Incorrect triggering with harmless neutral voltage occurs when using this combined Schutzschaitersteckers that the removal of the protective measure by pulling out the Slekker from the socket is irrelevant, since in this case the power supply of the device is all-pole at the same time is interrupted. In addition, when using a conventional socket; in Place the stipulated Schuko socket with the then missing protective conductor triggering the Circuit breaker * as soon as a defective device or cable is touched by an earthed person or otherwise comes into contact with the earth. The shutdown takes place within a very short time Time and in the case of non-hazardous currents, for example when exceeding 30 mA.

An embodiment of the invention is shown in the drawing, which shows the protective circuit

for a circuit breaker plug with extended residual current protection, additionally equipped with zener diodes to prevent false tripping in the event of an dangerous neutral voltage, shows.

The circuit breaker plug 10 is two-pole (T and Mp) on the mains side and has protective conductor contacts SL . The protective conductor is connected to the neutral conductor in the socket by a pressure. In the larger connector housing in front of the German wall connector, the known components of a residual current circuit breaker are housed, such as the summation current transformer with the primary windings W ₁ , as a trigger the residual current coil 11, the switch lock 12 and the switching compacts K ₁ . A switch toggle and the test button T for functional testing of the protective circuit are routed to the front of the housing. On the consumer side, the movable connection line 13 is inserted into the connector housing, which connects the circuit breaker plug to the consumer device 5 without an adapter.

The circuit according to the main patent is recognizable in that the protective conductor 51 in the residual current protective device is connected to the primary winding W _{3 of} the summation current transformer, the number of turns of which is twice as large as the number of turns of the primary windings W ₁ and W., for the connection of the neutral conductor and of the outer conductor, and that the protective conductor is routed via the switching contact K ₁₁ . As an example of the configuration of this circuit according to the invention to prevent false tripping in the case of a harmless neutral voltage, connect it to the circuit of the protective conductor! The limiting resistor 14 is connected to the switching contact K ₃ and then the two same Zener diodes 15 and 16 are connected in opposite directions. No protection is claimed for the features of claims "." And "3".

1 sheet of drawings

Claims (3)

i 809 claims: 1.Protective circuit with short response time for mobile consumer devices connected to earthed networks with a protective conductor, which is preceded by a residual current circuit breaker with a specified nominal residual current below 50mA, with which the protective conductor is routed through at least one switching contact of the residual current circuit breaker and to one or more in Series-connected primary windings of the summation current transformer of the circuit breaker, whose total number of turns is at least twice as large as the number of turns of one of the primary windings for the connection of an outer conductor or the neutral conductor, is connected according to the main patent 17 63 584, characterized in that in the residual current circuit breaker ( 10) a voltage-dependent resistor with a characteristic is connected in series in the circuit of the protective conductor, according to which the resistance ^l ~ -A is high for small voltages, but very low for higher voltages. 2. Protection circuit according to claim 1, characterized in that the spjnnungsabnangige Resistance of two identical, oppositely directed Zener diodes connected in series (IS, 16) formed v. Is. to those in Roil it- rm _ <■ Limiting resistor (14) is switched 3. Use a "protection circuit according to Claims 1 and 2, characterized in that it is built into a connector on the the net / ropes as - preferably two-pole "3; Wall plug designed with protective conductor cones is. and in the one on the consumer side movable genital connection is introduced.