| 摘要 |
The residual current device is provided with a summing current transformer whose secondary circuit contains a rectangular waveform generator, a measurement resistor and an electronic evaluation device. According to the invention, the secondary voltage (U1) and a control voltage (U2) are specified as input signals to the coupling switch (19). The coupling switch (19) contains one sensor (30, 30') and a tripping lock (40) for the tripping device (11), for each of these input signals (U1, U2). This residual current device is insensitive to brief, random surge currents and surge voltages (voltage spikes) which are produced, for example, by a lightning strike, even with a relatively low current intensity. <IMAGE>
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