Current sampling circuit and current range judging device thereof

Abstract

The invention discloses a current sampling circuit and a current range judging device thereof, which are used for current measurement of a transformer neutral point. The current range judging device comprises a preprocessing circuit, an absolute-value circuit, N comparison circuits and N isolating circuits. According to the invention, the measurement result of a Hall current sensor with maximum range in the current sampling circuit is input into the comparison circuits, the comparison result is directly input into an I / O (Input / output) port of a controller through the isolating circuits, and the range of the current measurement is directly judged by reading the electrical level of the I / O port, in this way, problems, such as that the Hall current sensor with small range can be easily damaged, the sampling circuit and the range judgment are more complex and processing time is too long, in the prior art are solved.

Description

technical field [0001] The invention relates to a current sampling circuit and its range judging device, in particular to a current sampling circuit at the neutral point of a transformer and its current range judging device. Background technique [0002] When the high-voltage DC system operates with a single-pole ground loop, a huge DC current flows into the ground through the DC ground electrode, and causes a significant change in ground potential in a wide range. This change in ground potential may cause damage to the AC system in the same area. influences. Two substations at different DC potentials form a loop through the transmission line, and the DC current is introduced into the neutral point of the transformer and the transformer winding, causing the DC bias phenomenon of the transformer, resulting in increased noise and vibration of the transformer, and may also cause overheating and AC damage. The harmonic distortion of the grid increases. The impact of this kind ...

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Problems solved by technology

[0005] In order to overcome the deficiencies in the above-mentioned prior art, the main purpose of the present invention is to provide a current sampling circuit and its current range judging device, which passes the measurement result of the Hall current sensor with the largest range into the comparison circuit, and the comparison result is passed through The isolation circuit is directly input to the I / O port of the controller, and the measurement range of the current measurement is directly determined by reading the level of the I / O port, which solves the problem that the Hall current sensor with a small range is easily damaged and the sampling circuit exists in the prior art. And the determination of the range is more complex and requires a long processing time and other issues

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