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Current Sensor Introduction

Definition and Basic Principles
- A current sensor is a device that can detect current signals and convert them into proportional electrical signals (usually voltage or digital signals) for output. Its working principles are mainly based on electromagnetic induction and the Hall effect. For a current transformer based on the principle of electromagnetic induction, when a current passes through the primary winding, a magnetic field is generated in the iron core, and this magnetic field induces a current in the secondary winding that is proportional to the primary current. The Hall - effect current sensor uses a Hall element. When a current passes through and generates a magnetic field, a Hall voltage is generated in a direction perpendicular to the magnetic field and the current, and this voltage is proportional to the measured current.
Main Types and Characteristics
- Open - loop Hall - effect Current Sensor
  - It has a simple structure and a relatively low cost. It has a fast response speed and can quickly detect current changes, but its accuracy is relatively lower than that of the closed - loop Hall - effect current sensor. It is suitable for applications where extremely high accuracy is not required, such as ordinary industrial motor current monitoring.
- Closed - loop Hall - effect Current Sensor
  - It has high accuracy and good linearity and can accurately measure current. It has strong anti - interference ability because its internal feedback winding can cancel out external magnetic field interference. However, it has a higher cost and is often used in scenarios where high accuracy and stability of current measurement are required, such as high - precision power systems and battery management systems of electric vehicles.
- Current Transformer
  - It can measure large currents and has high reliability. It is a traditional current - measuring tool, but it is relatively large in size and is generally used for the measurement of alternating current. It is widely used in current monitoring of high - voltage lines in power systems.
Application Areas
- Industrial Automation
  - In motor control systems, it is used to monitor the running current of motors in real - time to achieve precise control and protection of motors. By detecting the current, it can determine whether the motor is overloaded, locked - rotor, or other abnormal conditions, so that timely measures can be taken to improve production efficiency and equipment life.
- Power System
  - It is used to monitor the current in the power grid, including the incoming and outgoing line currents of substations and the currents of transmission lines. This is crucial for the safe and stable operation of the power system and can promptly detect fault currents, such as short - circuit currents, so that the faulty line can be quickly cut off to prevent the accident from expanding.
- New Energy Field
  - In solar photovoltaic power generation systems, it is used to monitor the output current of photovoltaic panels and the input and output currents of inverters to ensure the effective conversion and transmission of electrical energy. In the field of electric vehicles, precise measurement of battery charging and discharging currents helps to extend battery life and improve vehicle performance and safety.
- Consumer Electronics
  - In some high - end electronic products, such as laptop computers and mobile phone chargers, it is used to monitor the internal circuit current to achieve power management and protection functions and ensure the normal operation of the equipment and the safety of users.

Key Brands

LEM (Switzerland)
- LEM is a world - famous manufacturer of electrical quantity sensors. Its current - sensor products are known for their high precision, high reliability, and wide range of application adaptability. The products cover a measurement range from tiny currents to large currents of thousands of amperes and can meet the complex requirements of various industrial and power systems. For example, its Hall - effect current sensors are widely used in electric - vehicle motor - driving and battery - management systems, providing accurate current monitoring for the efficient operation and safety of vehicles.
Allegro (United States)
- The brand has accumulated deep technological strength in the field of sensor technology. Allegro's Hall - effect current sensors have the characteristics of high performance, small size, and low power consumption. Its products are widely used in automotive electronics, industrial control, and consumer electronics. In the automotive electronics field, its current sensors can provide accurate current measurement for various electronic systems of automobiles, such as engine - control units and electric - power - assisted - steering systems, helping to improve automobile performance and reliability.
VAC (Germany)
- VAC focuses on the research and development of magnetic materials and sensor technologies. Its current sensors are famous for their excellent precision and stability and are particularly suitable for applications where extremely high measurement accuracy is required. They perform well in high - precision industrial - automation equipment and high - end power - system current measurement, providing reliable data support for industrial production and power monitoring.
Honeywell (United States)
- Honeywell has a rich product line in the sensor field. Its current - sensor products are widely used in industrial control and aerospace. In industrial control, it can provide stable current monitoring for complex automated production lines; in aerospace, it meets the requirements of high - reliability and high - accuracy current measurement and provides security for the safe operation of aircraft electrical systems.