Device for measuring voltage by scanning

Abstract

Device for measuring voltage by sampling, including a voltage metering sampling means (2) driven by a pilot frequency generator (12), an amplifier (3) to amplify the sampled signal and a signal processing unit (6) to evaluate the amplified signal in accordance with the prescribed measuring task. The device, in accordance with the invention, contains an auxiliary oscillator (14) which produces an auxiliary signal, as well as an amplifier (3) with adjustable amplification, which is located between sampling unit (2) and signal processing unit (6), and a differential circuit (5). The auxiliary signal on one side, together with the voltage to be measured, is connected to signal input (17) of sampling unit (2), on the other side by means of a phase shifter (13) to an input (25) of differential circuit (5). A feedback branch (28), selective for the frequency of the auxiliary signal, is connected between, on one side, the output of differential circuit (5) and/or its other input (24) which is connected to adjustable amplifier (3) and, on the other side, the control input (21) of adjustable amplifier (3).

Dependencies are inferred from the claim text.