A non-invasive slow current measuring instrument and its preparation method

Abstract

The invention discloses a non-invasive slow current measuring instrument and a preparation method thereof. The non-invasive slow current measuring instrument comprises a measuring instrument probe and an amplification circuit; the measuring instrument probe comprises a magnet ring, a primary winding, a secondary winding and a feedback winding; the three windings insulated from one another are wound around the same magnet ring; the primary winding is connected to a current to be measured; the magnet ring is prepared from a soft magnetic material; the secondary winding is connected to the anode and cathode of the input end of the amplification circuit; the amplification circuit comprises an IV transformation circuit and two paths of operation amplifier output, one path is output after current following processing, and the other path of connected with one leading-out wire of the feedback winding; and the other leading-out wire of the feedback winding is common-ground electronically. The measuring instrument improves the low-frequency response performance, a current sensor has a wider bandwidth, the equivalent inductance is improved, the equivalent resistance is reduced, pulse drop time is prolonged, and the detected slow-change pulse current waveform is not distorted.

Description

technical field [0001] The present application relates to the field of current measuring equipment, in particular to a non-invasive slow current measuring instrument and a preparation method thereof. Background technique [0002] Current measurement is divided into two methods: intrusive and non-intrusive. Intrusive current measurement is based on the traditional Ohm's law, which has the advantages of low cost, high precision, and small size. The disadvantages are also very obvious, such as large temperature drift, difficult selection of precision resistors, and no isolation effect. Non-intrusive current measurement mainly includes current transformer (Current Transformer, CT), Hall sensor and other methods. Among them, the current transformer is the most widely used current measurement method in the electric energy metering device in our country. [0003] The current transformer is mainly composed of a primary winding, a secondary winding, an iron core, insulation between...

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Problems solved by technology

[0005] However, since the ferrite material used in the iron core of these products will be saturated under high current, and the iron core will also produce hysteresis after magnetization, unless it is demagnetized again, the accuracy will drop

Moreover, the existing current transformer has a small measurement dynamic range and a narrow frequency band, and cannot meet the requirement that the peak drop is less than 1% for the slow-changing pulse current with a flat top duration greater than 1 second

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