Patent ID: 6853180

Claim:
A measurement value detection and processing unit comprising: a measurement circuit which has at least one sampling unit, an analog/digital converter and a digital signal processing device, the sampling unit for sampling a measurement signal which is to be detected, the analog/digital converter for digitizing the sample values, the digital signal processing device for processing the digitized sample values, a switching unit, by way of which an electrical connection can be produced between the measurement circuit and a reference ground potential AGND, in which, when no measurement signal is being injected into the measurement circuit, only existing interference signals occurring in the measurement circuit are detected thereby, the digital signal processing device for numerical compensation, in which useful values of the measurement signal which are subject to interference components are compensated for by way of interference components which are detected in an isolated manner at relevant times, and the measurement value detection and processing unit determines the root mean square value I RMS of a current i 1 (t), to which a proportional voltage u 1 (t) corresponds, using the formula: I RMS1 = 1 N · ∑ n = 1 N ⁢ i1 ⁡ [ n ] 2 - ∑ n = 1 N ⁢ i0 ⁡ [ n ] 2 with the following definitions: i 1 [n] Digital sample value of the current i 1 (t) at the output of the A/D converter, i 0 [n] Digital sample value i 1 (t) at the output of the A/D converter with electrical connection of the measurement circuit to the reference ground potential AGND, and N Number of sample values for root mean square value calculation.