In modern power systems and electronic equipment, current measurement and monitoring are important links to ensure safe and stable operation of the system. Current sensors and current transformers are two common current measurement devices. Although their functions are similar, there are significant differences in structure, working principle, application scenarios, etc. This article will analyze the differences between current sensors and current transformers in detail from multiple perspectives to help readers better understand and choose appropriate measurement equipment.
1. Definition and basic principlesCurrent Transformer (CT) is an electrical device that uses the principle of electromagnetic induction to convert the large current of the primary circuit into the small current of the secondary circuit, which is convenient for measurement and protection devices. It usually consists of an iron core and windings, and realizes the transformation of current through electromagnetic induction.A current sensor is a device that converts a current signal into a measurable electrical signal (such as voltage or frequency). There are many types, including Hall effect sensors,shunt、resistancesensors, etc. Its working principle relies on different physical effects, such as Hall effect, resistor voltage reduction, etc.2. Differences in structural compositionThe current transformer has a relatively simple structure, mainly composed of an iron core and windings. It is large in size and suitable for installation in high-voltage power systems. The current output by its secondary winding is proportional to the primary current, making it easy to connect directly to an ammeter or relay protection device.Current sensors have various structures. Hall sensors usually contain a magnetic core and Hall element. They are compact and can achieve non-contact measurement. The shunt uses precision resistors to directly measure the voltage drop generated by the current. It has a compact structure and is suitable for low-voltage applications.3. Measurement accuracy and rangeCurrent transformers are suitable for measuring large currents and are usually used in high-voltage power systems. They have a wide and stable measurement range and accuracy levels generally ranging from level 0.1 to level 3 to meet the measurement and protection needs of power systems.The measurement range of current sensors varies according to different types. Hall sensors are suitable for small and medium current measurements. They have high accuracy and fast response speed, and are suitable for dynamic monitoring. The shunt has high accuracy, but it is mainly used for low-voltage DC or AC current measurement and will cause certain power loss.4. Installation method and safetyCurrent transformers need to be connected in series in the primary circuit, and the circuit needs to be disconnected during installation. The operation is complicated and there are certain safety risks. Its secondary circuit must be kept closed, otherwise high voltage may be generated, endangering equipment and personnel.Most current sensors implement non-contact measurement, especially Hall effect sensors, which are easy to install, do not require power-off operation, and are highly safe. Although the shunt needs to be connected in series, it is small in size and flexible in installation, making it suitable for embedded applications.5. Differences in application areasCurrent transformers are mainly used in current measurement, metering and protection of power systems, and are especially suitable for high voltage and strong current environments, such as substations, power plants, etc.Current sensors are widely used, covering industrial automation, home appliance control, electric vehicles, battery management systems, etc. Its diverse measurement methods make it suitable for a variety of current types and measurement needs.6. Response speed and dynamic performanceCurrent sensors, especially Hall sensors, have fast response times and can monitor current changes in real time, making them suitable for dynamic control and protection.The response speed of current transformer is relatively slow and suitable for steady-state measurement and protection actions. Its dynamic performance is generally not as good as that of current sensors.7. Cost and MaintenanceCurrent transformers have low manufacturing costs and simple structures, but are large in size and require cumbersome installation and maintenance.The cost of current sensors varies depending on the type. Hall sensors are more expensive, but are easy to install and maintain, making them suitable for intelligent applications.：电流传感器和电流互感器虽然都用于电流的测量与监控，但在定义、结构、测量范围、安装方式、安全性、应用领域、响应速度及成本等方面存在明显差异。电流互感器适合高压大电流的测量和电力系统的保护，结构简单但安装复杂；电流传感器种类丰富，适合多场景多类型电流测量，安装方便且动态性能优越。选择何种设备应根据具体应用需求、电流大小、测量精度和环境条件综合考量，才能达到最佳测量效果和系统安全保障。
