High-precision micro-current sensor

Abstract

The utility model relates to the technical field of power grid insulation monitoring, and discloses a high-precision micro-current sensor, which comprises a current transformer and an operational amplifier circuit module, a measuring circuit module is arranged in the current transformer, the current transformer is used for converting micro-current signals in the measuring circuit module, and the operational amplifier circuit module is used for amplifying the micro-current signals. A small current signal is converted into a measurable and processable voltage signal, the operational amplifier circuit module amplifies the converted voltage signal, a cable shielding layer penetrates through a sensor through hole and then is grounded, and when a grounding fault occurs in a system where a cable is located, part of fault current flows to the ground through the shielding layer, and the fault current is detected. When the current passes through the interior of the high-precision micro-current sensor, a micro-current signal is converted into a voltage signal through the high-precision micro-current sensor and then is amplified, so that the magnitude of the measured current can be accurately measured, and meanwhile, the high-precision micro-current sensor is small in size and high in anti-interference capability.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of power grid insulation monitoring, specifically to a high-precision micro-current sensor. BACKGROUND

[0002] The current sensor is a detection device that can sense the information of the measured current and convert it into an electrical signal or other required form of information output according to certain rules to meet the requirements of information transmission, processing, storage, display, recording, and control. It is generally used for power system monitoring to monitor the current direction and size in the power system and timely discover and solve problems in the circuit.

[0003] By setting the current sensor to monitor the insulation state of the power grid in real time, the current sensor can effectively prevent power accidents caused by insulation failure, such as leakage and short circuit, thereby ensuring the safe operation of the power system.

[0004] According to the existing related technology, the inventor believes that the following defects exist: the traditional current sensor has poor precision and linearity when measuring small current and is easily disturbed. INVENTION CONTENTS

[0005] To solve the technical problem that the existing current sensor has poor precision and linearity when measuring small current and is easily disturbed, the utility model provides a high-precision micro-current sensor.

[0006] The utility model adopts the following technical scheme: a high-precision micro-current sensor, comprising a current transformer and an operational amplifier amplification circuit module, a measurement circuit module is arranged inside the current transformer, the current transformer is used for converting the small current signal in the measurement circuit module, so that the small current signal is converted into a measurable and processable voltage signal, and the operational amplifier amplification circuit module amplifies the converted voltage signal.

[0007] Preferably, a high-resistance resistor is arranged in the measurement circuit to form a bridge circuit, when a small current signal passes through the high-resistance resistor, a small voltage change is caused in the measurement circuit, and the small voltage change is amplified at the operational amplifier amplification circuit module.

[0008] Preferably, the current transformer is composed of a coil and a magnetic core.

[0009] Preferably, a through hole is processed inside the high-precision micro-current sensor, and a cable shielding layer is arranged inside the through hole.

[0010] Preferably, the cable shielding layer is grounded after passing through the through hole.

[0011] Compared with the prior art, the utility model has the advantages that:

[0012] The utility model discloses when using, through the cable shielding layer is grounded after passing through sensor through -hole, when the system of cable is grounded failure, part of the fault current will flow to the earth through the shielding layer, when the current passes through the inside of high accuracy micro - current sensor, through high accuracy micro - current sensor will little current signal conversion voltage signal after amplification, can accurate measurement measurement current size, and high accuracy micro - current sensor is small, and the anti -interference ability is strong. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is the cable shielding layer through high accuracy micro - current sensor schematic diagram of the utility model. DETAILED DESCRIPTION

[0014] Below, combining the drawings and specific implementation, the utility model is described further, need explaining, under the premise of not conflicting, the following described each embodiment between or each technical feature between can be any combination formation new embodiment.

[0015] Embodiment 1: please refer to Figure 1 The utility model discloses a kind of high accuracy micro - current sensors of the embodiment, including current transformer and operational amplifier amplification circuit module, current transformer is composed of coil and magnetic core, current transformer is provided with measurement circuit module inside, current transformer its function is to convert the little current signal in measurement circuit into voltage signal easy to measure and handle, then the Hall voltage of two sides is measured, the current size is calculated by Hall voltage and the calibration coefficient of sensor, finally voltage signal is further amplified by operational amplifier amplification circuit module, to improve measurement accuracy;

[0016] Wherein, using the magnetic field coupling effect in current transformer, a high resistance resistance can be formed in measurement circuit by adding an electric bridge circuit, at this time, little current signal is added to the resistance, a little voltage change will be caused in current transformer, and this change will be amplified by operational amplifier circuit, so as to carry out subsequent measurement and processing;

[0017] Further, high accuracy micro - current sensor is internally machined with through -hole, cable shielding layer is arranged in through -hole, cable shielding layer is grounded after passing through through -hole, high accuracy micro - current sensor is generally installed outside cable shielding layer, for the purpose of safety and anti-interference etc., cable shielding layer is grounded after passing through sensor through -hole, when the system of cable is grounded failure, cable insulation is damaged, phase line is in contact with shielding layer, part of the fault current will flow to the earth through the shielding layer, current will pass through the inside of high accuracy micro - current sensor, so that little current signal is converted into voltage signal by high accuracy micro - current sensor, and then amplified, to facilitate accurate measurement.

[0018] Working principle: through the cable shielding layer passes through the sensor through -hole and connects the ground, when the system where the cable is located occurs grounding fault, part of the fault current will flow to the ground through the shielding layer, when the current passes through the inside of the high-precision micro-current sensor, the high-precision micro-current sensor converts the tiny current signal into a voltage signal and then amplifies, so that the measurement current size can be accurately measured, and the high-precision micro-current sensor is small in size and strong in anti-interference capability.

[0019] The above-mentioned embodiments are only preferred embodiments of the utility model, and cannot be used to limit the range of the utility model protection, and any non-substantial change and replacement made by the person skilled in the art on the basis of the utility model belongs to the range of the utility model claimed for protection.

Claims

1. A high-precision micro-current sensor comprising a current transformer and an operational amplifier amplification circuit module, characterized in that, The current transformer is internally provided with a measurement circuit module, which is used to convert a tiny current signal in the measurement circuit module, so that the tiny current signal is converted into a measurable and processable voltage signal, and the operational amplifier amplification circuit module amplifies the converted voltage signal.

2. The high-precision micro-current sensor according to claim 1, wherein A high-resistance resistor is arranged in the measurement circuit to form a bridge circuit, and when a tiny current signal passes through the high-resistance resistor, a tiny voltage change is caused in the measurement circuit, and the tiny voltage change is amplified at the operational amplifier amplification circuit module.

3. The high-precision micro-current sensor according to claim 1, wherein The current transformer is composed of a coil and a magnetic core.

4. The high-precision micro-current sensor according to claim 1, wherein, The high-precision micro-current sensor is internally machined with a through hole, and the through hole is internally provided with a cable shielding layer.

5. A high precision micro-current sensor according to claim 4, characterized in that, The cable shielding layer is grounded after passing through the through hole.

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