DE3409603A1 - Earth-leakage current protection circuit breaker - Google Patents

Abstract

The invention relates to an earth-leakage current protection circuit breaker having a summing current transformer (2) in whose secondary circuit a triggering device (3) is connected which is in engaged connection (5) with a latching mechanism (4). The latching mechanism (4) acts on a switching contact (6) in the line (1) which is to be monitored. It is provided that the triggering device (3) can be bridged-over between its connecting leads (7, 8) by a low-pass filter (9) which short-circuits radio-frequency voltages. <IMAGE>

Description

SIEMENS AKTIENGESELLSCHAFT Our mark Berlin and Munich VPA 84 P 3 0 9 9 DE

Residual current circuit breaker r

The invention relates to a residual current circuit breaker with a summation current transformer in its secondary circuit a trip device is connected, which is connected to a switch lock in engagement connection, which is on a Switching contact acts in the line to be monitored.

Such residual current circuit breakers are known (DE-OS 32 30 557). In the secondary circuit, the summation current transformer is connected in series with the tripping device

• .ε capacitor arranged. This capacitor is on the Frequency in the secondary circuit, at least roughly resonant, with a primary-side fault current Causes direct current components on the secondary side. This makes the residual current circuit breaker sensitive

2Q for residual currents with direct current components.

The connection lines to the release device are bridged by a voltage-dependent resistor, whose resistance value falls above a threshold with increasing voltage. The threshold becomes like this chosen that it is just above the response voltage of the trip device. Voltage peaks Surge currents that are above the threshold are short-circuited in front of the release device.

Also residual current circuit breakers, the release mechanism of which works independently of the frequency of the mains voltage, have already been proposed (registration with older priority P 32 44 670.5). In the secondary

MnI 2 Sir / 03/13/1984

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circuit between summation current transformer and tripping device switched on a rectifier arrangement, which acts as a bridge rectifier can be formed.

Such a residual current circuit breaker, which is also safe in the event of high residual currents of high frequency triggers, has also already been proposed (registration with older priority P 33 28 084.3). Included an electronic valve consisting of two diodes connected in series is arranged parallel to the release device. The response voltage of the diodes is above the response voltage of the release device.

Such residual current circuit breakers work in conjunction with switching operations in a low-voltage network With very long cables, due to the high cable capacities, they are not secure enough against false tripping.

In an electrical low-voltage network with inductive loads come in connection with line capacities compensatory oscillations during switching operations. The overvoltage occurring in the circuit can be multiple the operating voltage. These high-frequency overvoltages dissolve in long cables across the Line capacitances from the outer conductor to the protective conductor from high-frequency leakage current oscillation packets, which one Bring upstream residual current circuit breaker to trip. Such cases can mainly be found in large buildings such as industrial plants, hospitals or office buildings occur when the protective conductor is in a very long line is carried and z. B. fluorescent lamps, motors or control transformers be switched.

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The invention is based on the object of a residual current circuit breaker to develop through high-frequency vibration packets, such as those in the low-voltage network caused by switching operations and transmitted via the summation current transformer, is not triggered. So you want to avoid false tripping.

According to the invention, this object is achieved in that the release device is located between its connecting lines is bridged by a low-pass filter that short-circuits high-frequency voltages.

Low frequencies that are supposed to trigger the residual current circuit breaker are let through by the low-pass filter. High-frequency vibrations, on the other hand, which cause false tripping of the residual current circuit breaker, are avoided by the Low pass blocked.

According to one embodiment, a TT element with two capacitors arranged in parallel can be switched on as a low-pass filter between the connecting lines. In this case, an ohmic or inductive resistor is arranged in series with the triggering device between their connection points in a connection line.
25th

The invention is intended to be more detailed with the aid of exemplary embodiments shown roughly schematically in the drawing explained:

Fig. 1 illustrates a first embodiment

of the residual current circuit breaker. Fig. 2 shows a residual current circuit breaker, which also works surge proof.

Fig. 3 illustrates a residual current circuit breaker, which is also surge current-proof and frequency-independent is working.

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The residual current circuit breaker according to FIG. 1 monitors a line 1 which contains the primary winding of a summation current transformer 2. In the secondary circuit of the summation current transformer 2, a release device 3 is arranged, which is in engagement connection 5 with a switch lock 4. This switch mechanism 4 acts on a switching contact 6 in the line 1 to be monitored.

A further capacitor 10 arranged in series with the tripping device 3 provides fault current protection switch sensitive to fault currents with DC components.

In a residual current circuit breaker according to FIG. 2, the connecting lines 7, 8 of the tripping device 3 are also bridged by a voltage-dependent resistor 11. As a result, the release device 3 is also high in front of Protected against electrical surges.

The residual current circuit breaker according to FIG. 3 has a low-pass filter for filtering out high-frequency oscillations TX element with capacitors 91, 92 arranged in parallel. Between the connection points of the capacitors 91, 92, a resistor 93 is arranged in the connection line 7 in series with the release device 3. Of the Low-pass can also consist of one or more chained or parallel-connected T-links or TT-links, wired with ohmic resistors, inductors and Capacities or their individual components exist. A bridge rectifier 12 is connected to a bridge branch the secondary winding of the summation current transformer 2 in connection. The release mechanism is on the other branch of the bridge

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3 connected. This bridge rectifier 12 makes the residual current circuit breaker independent of the mains frequency. Two series-connected diodes 13 in parallel with the tripping device 3 ensure that the residual current circuit breaker triggers safely even with high fault currents and high frequency. Compare FIG. 3.

2 claims

3 figures

Claims (2)

3409603 VPA MP 3 0 9 9 DE claims (I.) Residual current circuit breaker with a summation current transformer ier (2), in the secondary circuit of which there is a release device (3) is connected, which is in engagement connection (5) with a switch lock (4), which is on a switching contact (6) acts in the line to be monitored (1), characterized in that the Tripping device (3) is bridged between its connecting lines (7, 8) by a low-pass filter (9), the high-frequency Short-circuits voltages. 2. Residual current circuit breaker according to claim 1, characterized in that as Low-pass filter between the connecting lines (7, 8) a TT element with two capacitors (91, 91, arranged in parallel) 92) is switched on, between the connection points in a connection line (7) an ohmic or inductive Resistor (93) is arranged in series with the release device (3).