| 摘要 |
The invention relates to a connecting circuit for a potential-free oxygen probe having a low-potential line and a high-potential line and includes: an amplifier; an offset voltage source connected to the high-potential line forward of the amplifier for applying an offset potential to the high-potential line; the amplifier having an input connected across the high-potential and low-potential lines to receive the difference between the potentials on the lines as an input voltage; the amplifier being adapted to amplify the input voltage and having an output for supplying an output voltage equal to the difference between the offset voltage and the amplified input voltage; and, the offset voltage being selected so as to cause the output voltage to always be greater than zero but less than a pregiven threshold voltage. This connecting circuit makes it possible to determine faults for probe connections, for example, short circuits of the line to ground. The output voltage then drops to 0 V which is not possible for proper operation in view of the offset voltage used. The threshold voltage is exceeded for shorts to battery potential. A method for checking for a correct probe connection is also disclosed. |
