Title: Temperature compensated combined current and voltage measuring apparatus

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Abstract: The combined current and voltage measuring apparatus has a cast resin body which supports the current measuring unit. The voltage measuring unit includes a capacitive voltage divider with an amplifier connected thereto. The cast resin body is also utilized as dielectric for the capacitor on the high-voltage side of the capacitive voltage divider. Embedded in the cast resin body is an auxiliary capacitor with a dielectric which, with respect to temperature dependence, corresponds to the dielectric of the high-voltage capacitor. The auxiliary capacitor, in series with a resistor, is connected to an auxiliary generator. The voltage dropped across the resistor is supplied, after rectification, to an input of a differential amplifier; the other input of the differential amplifier is connected to the terminal away from ground of the capacitor on the low-voltage side of the capacitive voltage divider. With respect to the capacitors of the capacitive voltage divider, a warming of the capacitor on the high-voltage side different from the warming of the capacitor on the low-voltage side does not influence the measuring accuracy of the capacitive voltage measuring unit of the apparatus.


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