Abstract: A signal transmission system for transmitting a main process variable and further data between a field device and a superordinate unit, includes a first conversion arrangement, a second conversion arrangement and an optocoupler arrangement. The optocoupler arrangement is connected between the first conversion arrangement and the second conversion arrangement. The first conversion arrangement is configured to convert at least the further data exchanged between the field device and the superordinate unit into a data signal transmittable via the optocoupler arrangement. The optocoupler arrangement transmits the data signal between the first conversion arrangement and the second conversion arrangement. The second conversion arrangement converts the data signal to the further data and transmits it to the field device. A method transmits a main process variable and further data between a field device and a superordinate unit. In the method, at least the further data is transmitted via an optocoupler arrangement.

Abstract: The invention relates to a protective circuit for an electrical device operated in particular in an explosion-hazard area, with a limiting circuit connected downstream of a pair of input terminals for limiting an output voltage present at a pair of output terminals and/or an output current delivered at the output terminals below a threshold value and a shorting circuit, which shorts the output or input terminals when a threshold value is exceeded, the control signal that controls the limitation originating from the same place as the signal that triggers the shorting circuit, and with a measuring circuit, which uses the output voltage or the output current to provide a control signal, which is fed on the one hand to a final control element for reducing the output voltage or the output current and on the other hand to the shorting circuit, the measuring circuit comprising a ZENER diode and/or a measuring resistor and the control signal being a voltage that is in particular a transistor-amplified or impedance-co

Abstract: The invention relates to a switching device for galvanically isolated 1:1 transmission of a direct current signal, with a transformer comprising a primary coil and a secondary coil, wherein the primary coil is powered with alternating current derived from an input direct current and the current induced in the secondary coil is rectified, and with a correction device for compensating transmission losses. To provide a DC transducer free of auxiliary energy, in which the output current is as close to equaling the input current as possible, it is proposed that the number of turns on the primary coil should be greater than the number of turns on the secondary coil.

Abstract: The invention relates to a protective circuit for an electrical device operated in particular in an explosion-hazard area, with a limiting circuit connected downstream of a pair of input terminals for limiting an output voltage present at a pair of output terminals and/or an output current delivered at the output terminals below a threshold value and a shorting circuit, which shorts the output or input terminals when a threshold value is exceeded, the control signal that controls the limitation originating from the same place as the signal that triggers the shorting circuit, and with a measuring circuit, which uses the output voltage or the output current to provide a control signal, which is fed on the one hand to a final control element for reducing the output voltage or the output current and on the other hand to the shorting circuit, the measuring circuit comprising a ZENER diode and/or a measuring resistor and the control signal being a voltage that is in particular a transistor-amplified or impedance-co

Abstract: The invention relates to a switching device for galvanically isolated 1:1 transmission of a direct current signal, with a transformer (3) comprising a primary coil (1) and a secondary coil (2), wherein the primary coil (1) is powered with alternating current derived from an input direct current (I1) and the current induced in the secondary coil (2) is rectified, and with a correction device (4) for compensating transmission losses. To provide a DC transducer free of auxiliary energy, in which the output current is as close to equaling the input current as possible, it is proposed that the number of turns on the primary coil (1) should be greater than the number of turns on the secondary coil (2).