Digital leakage current detection circuit and detection method thereof

Abstract

The invention discloses a digital leakage current detection circuit and a detection method thereof. The circuit comprises a leakage detection transformer and a detection control circuit connected with the leakage detection inductor, a detection signal reverse connection circuit is arranged on a connection loop of the leakage detection transformer and the detection control circuit, the detection control circuit consists of a singlechip with a built-in analog comparator, and excitation sources are connected on a loop between the signal reverse connection circuit and the detection control circuit in series. Constant excitation voltage is applied on the magnetic ring of the leakage detection transformer in a cyclic and opposite mode in the detection signal reserve connection circuit; sampling digital wave forms are adopted to calculate the magnitude and plus-minus of time difference when phase reversal reaches magnetic saturation twice, which also reflect the current size and direction ofa detected object; and measurement on the leakage current Ix can be realized based on Ix=k*delta t.

Description

technical field [0001] The invention relates to an electromagnetic measurement technology, in particular to a digital leakage current detection circuit and a detection method thereof. Background technique [0002] At present, there are many magnetic modulation circuits and detection methods. The detection methods are limited by the stability of the magnetic ring. The main problems are: (1) Drift with temperature. At different temperatures, the zero point of the transformer will drift. As a result, the measurement error increases; (2) As time goes by, the residual magnetism of the accumulated magnetic core is difficult to solve, and it often needs to be adjusted again on site; (3) It is easily affected by the geomagnetism, and the transformers that have been calibrated before leaving the factory are transported to different A second calibration is often required after the area. [0003] Chinese patent application number is 98106874.X patent document "Phase difference magneti...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a circuit and detection method for electromagnetically measuring DC leakage current in view of the zero point drift problem caused by the magnetic ring in the prior art that is susceptible to the influence of geomagnetism, temperature changes and residual magnetism.

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