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An active protective circuit for a measuring amplifier of an electrical impedance tomograph includes a circuit component arrangement including an electrode input and an output and a control input for a control voltage. The output is configured for connection to a measuring amplifier for an electrica

An active protective circuit for a measuring amplifier of an electrical impedance tomograph includes a circuit component arrangement including an electrode input and an output and a control input for a control voltage. The output is configured for connection to a measuring amplifier for an electrical impedance tomograph. The circuit component arrangement creates a conductive connection between the electrode input of the circuit component arrangement and the output of the circuit component arrangement when the applied control voltage is within a first voltage range and does not create a conductive connection when the applied control voltage is within a second voltage range. The voltage being applied to the control input is within the second voltage range when a voltage, which is within a cut-off range, is applied to the electrode input. An electrode belt for impedance tomography has the active protective circuits associated with the electrodes.

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1. An electrical impedance tomograph measuring amplifier active protective circuit comprising: a circuit component arrangement comprising: an electrode input configured for connection to an electrode of an electrode belt for an electrical impedance tomograph;an output configured for connection to a

1. An electrical impedance tomograph measuring amplifier active protective circuit comprising: a circuit component arrangement comprising: an electrode input configured for connection to an electrode of an electrode belt for an electrical impedance tomograph;an output configured for connection to a measuring amplifier of an electrical impedance tomograph;at least one control input for a control voltage; andat least one conductive connection circuit component configured to create a conductive connection between the electrode input and the output when the control voltage, applied to the control input, is within a first voltage range and to not create a conductive connection between the electrode input and the output when the control voltage, applied to the at least one control input, is within a second voltage range; andat least one control voltage regulation circuit configured such that the control voltage, applied to the control input, is within the second voltage range when a voltage, within a cut-off range, is applied to the electrode input, the control voltage regulation circuit comprising a blocking component connecting the output to the at least one control input, wherein the blocking component is configured such that the voltage applied to the output is only applied to the control input if the voltage being applied to the output is within the cut-off range. 2. An active protective circuit in accordance with claim 1, further comprising a bypass circuit parallel to the circuit component arrangement, the bypass circuit connecting the input of the circuit component arrangement to the output of the circuit component arrangement, wherein the bypass circuit is configured such that a voltage within the cut-off range is applied to the output of the circuit component arrangement when the circuit component arrangement does not create a conductive connection between the electrode input of the circuit component arrangement and the output of the circuit component arrangement, and the voltage being applied to the electrode input of the circuit component arrangement is within a high-volt range, wherein the high-volt range is a partial range of the cut-off range. 3. An active protective circuit in accordance with claim 1, wherein the control voltage regulation circuit comprises a memory circuit configured such that a voltage, which is within the second voltage range, is continuously applied to the at least one control input when a voltage, which is within the cut-off range, is applied once to the electrode input. 4. An active protective circuit in accordance with claim 1, wherein the cut-off range is defined by a lower voltage limit between 40 V and 10 V. 5. An active protective circuit in accordance with claim 1, wherein the cut-off range is defined by a lower voltage limit of about 20 V. 6. An active protective circuit in accordance with claim 1, wherein the cut-off range has two sections, wherein a first section comprises all voltages less than −10 V and a second section comprises all voltages greater than 10 V. 7. An active protective circuit in accordance with claim 1, wherein the cut-off range has two sections, wherein a first section comprises all voltages less than −20 V, and a second section comprises all voltages greater than 20 V. 8. An electrical impedance tomograph measuring amplifier active protective circuit, comprising: a circuit component arrangement comprising: an electrode input configured for connection to an electrode of an electrode belt for an electrical impedance tomograph;an output configured for connection to a measuring amplifier of an electrical impedance tomograph;at least one control input for a control voltage; andat least one conductive connection circuit component configured to create a conductive connection between the electrode input and the output when the control voltage, applied to the control input, is within a first voltage range and to not create a conductive connection between the electrode input and the output when the control voltage, applied to the at least one control input, is within a second voltage range; andat least one control voltage regulation circuit configured such that the control voltage, applied to the control input, is within the second voltage range when a voltage, within a cut-off range, is applied to the electrode input, wherein: the at least one conductive connection circuit component comprises a component input connected to the electrode input, a component output connected to the output of the circuit component arrangement and a control input connected to the at least one control input of the circuit component arrangement;the at least one conductive connection circuit component is configured to provide a conductive connection between the component input and the component output, when the control voltage is within the first voltage range and to not provide a conductive connection between the component input and the component output when the control voltage is within the second voltage range; andthe at least one control voltage regulation circuit is configured such that the control applied to the at least one control input switches to the second voltage range when a voltage, which exceeds a predefined first threshold value, is applied to the electrode input. 9. An active protective circuit in accordance with claim 8, wherein: the at least one conductive connection circuit component comprises a normally off n-channel MOSFET with a drain terminal, a source terminal and a gate terminal;the drain terminal forms the component input, the source terminal forms the component output and the gate terminal forms the component control input. 10. An active protective circuit in accordance with claim 8, wherein: the control voltage regulation circuit comprises a blocking component connecting the output to the at least one control input, wherein the blocking component is configured such that the voltage applied to the output is only applied to the control input if the voltage being applied to the output is within the cut-off range;the component output is connected to the component control input via the blocking component;the blocking component is configured such that the voltage being applied to the component output is only applied to the component control input if the voltage being applied to component output is within the cut-off range;the blocking component comprises two series-connected Z diodes, wherein each Z diode has a conducting direction and a blocking direction, and wherein the two series-connected Z diodes are interconnected such that the conducting direction of one of the Z diodes corresponds to the blocking direction of another of the Z diodes. 11. An active protective circuit in accordance with claim 10, further comprising a bypass circuit parallel to the circuit component arrangement, the bypass circuit connecting the input of the circuit component arrangement to the output of the circuit component arrangement, wherein: the circuit component arrangement is configured such that a voltage within the cut-off range is applied to component output does not create a conductive connection between the electrode input and the component output, and the voltage being applied to the electrode input is within the high-volt range; andthe bypass circuit has at least one high-ohmic resistor. 12. An active protective circuit in accordance with claim 8, wherein: the control voltage regulation circuit comprises a memory circuit configured such that a voltage, which is within the second voltage range, is continuously applied to the at least one control input when a voltage, which is within the cut-off range, is applied once to the electrode input; andthe memory circuit is formed by a flip-flop. 13. An active protective circuit in accordance with claim 8, wherein: the at least one conductive connection circuit component is a first component and the component input is a first component input, the component output is a first component output and the component control input is a first control input;the circuit component arrangement further comprises at least a second control input and at least a second conductive connection circuit component with a second component input, a second component output and a second component control input;the second component input is connected to the electrode input, the second component output is connected to the output of the circuit component arrangement, and the second component control input of the second circuit component is connected to the second control input;the first circuit components and the second circuit component are connected in series with the component input connected to the second component output;the second circuit component is configured to provide a conductive connection between the second component input and the second component output when the control voltage applied to the second component control input is within a third voltage range, and to not provide a conductive connection between the second component input and the second component output when the control voltage applied to the second component control input is within a fourth voltage range;the control voltage regulation circuit is configured such that the voltage applied to the second component control input switches to the fourth voltage range when a voltage, which falls below a predefined second threshold value, is applied to the electrode input. 14. An active protective circuit in accordance with claim 13, wherein: the second circuit component comprises a p-channel MOSFET with a drain terminal, a source terminal and a gate terminal; andthe drain terminal forms the second component input, the source terminal forms the second component output, and the gate terminal forms the second component control input. 15. An electrical impedance tomograph electrode belt comprising: a plurality of electrodes;a plurality of active protective circuits, wherein at least one active protective circuit is associated with each electrode, and each active protective circuit is associated with only one electrode, wherein each active protective circuit comprises:a circuit component arrangement comprising: an electrode input configured for connection to an electrode of an electrode belt for an electrical impedance tomograph;an output configured for connection to a measuring amplifier of an electrical impedance tomograph;at least one control input for a control voltage;at least one conductive connection circuit component configured to create a conductive connection between the electrode input and the output when the control voltage, applied to the control input, is within a first voltage range and to not create a conductive connection between the electrode input and the output when the control voltage, applied to the at least one control input, is within a second voltage range; andat least one control voltage regulation circuit configured such that the control voltage, applied to the control input, is within the second voltage range when a voltage, within a cut-off range, is applied to the electrode input, wherein the electrode input of the circuit component arrangement of each active protective circuit is connected to the respective electrode with which the active protective circuit is associated. 16. An electrode belt in accordance with claim 15, wherein the control voltage regulation circuit comprises a blocking component connecting the output to the at least one control input, wherein the blocking component is configured such that the voltage applied to the output is only applied to the control input if the voltage being applied to the output is within the cut-off range. 17. An electrode belt in accordance with claim 16, further comprising a bypass circuit parallel to the circuit component arrangement, the bypass circuit connecting the input of the circuit component arrangement to the output of the circuit component arrangement, wherein the bypass circuit is configured such that a voltage within the cut-off range is applied to the output of the circuit component arrangement when the circuit component arrangement does not create a conductive connection between the electrode input of the circuit component arrangement and the output of the circuit component arrangement, and the voltage being applied to the electrode input of the circuit component arrangement is within a high-volt range, wherein the high-volt range is a partial range of the cut-off range. 18. An electrode belt in accordance with claim 15, wherein the control voltage regulation circuit comprises a memory circuit configured such that a voltage, which is within the second voltage range, is continuously applied to the at least one control input when a voltage, which is within the cut-off range, is applied once to the electrode input. 19. An electrode belt in accordance with claim 15, wherein: the at least one conductive connection circuit component comprises a component input connected to the electrode input, a component output connected to the output of the circuit component arrangement and a control input connected to the at least one control input of the circuit component arrangement;the at least one conductive connection circuit component is configured to provide a conductive connection between the component input and the component output, when the control voltage is within the first voltage range and to not provide a conductive connection between the component input and the component output when the control voltage is within the second voltage range; andthe at least one control voltage regulation circuit is configured such that the control applied to the at least one control input switches to the second voltage range when a voltage, which exceeds a predefined first threshold value, is applied to the electrode input.