The difference between current sensor and current transformer

In the field of modern electrical measurement and control, current sensors and current transformers are two common current detection devices. Although they are both used to measure current, there are significant differences in structure, principle, application scenarios, etc. This article will introduce in detail the differences between current sensors and current transformers to help readers better understand and choose appropriate measurement tools.

Current Transformer (CT) is a conversion device that uses the principle of electromagnetic induction to convert high current into low current. It is mainly used for measuring AC current. It induces a current proportional to the primary current in the secondary winding through the magnetic field generated by the primary side conductor.

Current sensors are a broader class of devices that convert current signals into easily processed electrical signals (such as voltage, current, or digital signals). Current sensors include Hall effect sensors,resistanceshunt, photoelectric sensors, etc., suitable for measurement of AC and DC current.

Current transformers are mainly used for AC current measurement, especially suitable for high current situations. They are commonly used in power systems and large industrial equipment. It is not suitable for DC current measurements.

There are various types of current sensors. Some are specialized in measuring DC current (such as Hall effect sensors), while others support both AC and DC current measurements and have a wider range of applications.

Current transformers have high accuracy and linearity within the rated range and are suitable for the measurement and protection needs of power systems.

The accuracy of current sensors varies depending on the type. Hall effect sensors have better linearity, but are greatly affected by temperature and magnetic field interference; shunts have high accuracy but have problems with power consumption and heating.

Current transformers are usually large in size, require windings and iron cores, require space for installation, and are usually installed on cables or busbars.

Current sensors are small in size and flexible in installation. Some adopt non-contact designs (such as Hall effect sensors) to facilitate quick installation and maintenance on site.

The current transformer achieves electrical isolation between the high-voltage side and the low-voltage side through transformer isolation, which has high safety.

Some current sensors, such as shunts, are directly connected in series in the circuit and have poor insulation performance, and their safety depends on the design and installation environment; Hall sensors have certain isolation capabilities.

The frequency response of current transformer is narrow, mainly for 50Hz or 60Hz power frequency current measurement, and the dynamic response is slow.

Current sensors, especially Hall effect sensors, have a wide frequency response and can measure rapidly changing current signals, making them suitable for electronic equipment and motor control fields.

The manufacturing process of current transformers is mature and the cost is moderate, but they are large in size and heavy in weight, and need to be powered off during maintenance.

Most current sensors are electronic components, which are small in size, light in weight, and easy to install and maintain. The cost varies greatly depending on the model and function.

Current sensors and current transformers each have their own advantages and applicable fields. Current transformers are suitable for high current AC measurements, have good isolation performance and stability, and are widely used in power systems. Current sensors are rich in types and have a wide range of applications. They can measure DC and AC currents and are suitable for electronic equipment and industrial automation fields. Choosing appropriate equipment based on actual needs can ensure measurement accuracy and system safety, and improve overall operating efficiency. Understanding the difference between the two can help engineers and technicians make the best decisions during the design and maintenance process.