HAT400-S Hall Effect Open-Loop Current Sensor

Precision, Reliability, Safety – The Core Component for Current Measurement in Industrial and Energy Applications

Brand: LEM – Global Leader in Current and Voltage Measurement Solutions
Product Series: HAT Series

In power electronics system design, the accuracy and reliability of current measurement directly impact overall operational stability and safety. The LEM HAT400-S Hall effect open-loop current sensor is designed for high-precision isolated measurement of DC, AC, and pulsed currents. With a rated current of 400 A, a maximum measuring range of ±1200 A, and an output response time of less than 5 μs, this sensor combines high accuracy, low power consumption, strong immunity, and wide temperature operation. It is widely used in variable frequency drives, switchmode power supplies, battery management systems, renewable energy grid integration, railway traction, and industrial automation.

HAT400-S Key Advantages

High Accuracy for Stable System Operation

The HAT400-S uses mature Hall-effect open-loop technology. With a rated current of 400 A and the ability to measure instantaneous currents up to ±1200 A, it achieves an accuracy of ±1% FS and linearity of ±1%. It delivers reliable and consistent measurement results across the full range, enabling more precise system control and protection.

High Isolation Voltage for System Safety

An electrical isolation voltage of 3000 V is provided between the primary (power) circuit and the secondary (measurement) circuit. The housing is made of UL 94-V0 rated insulating plastic. Whether used in high-power variable-frequency equipment or high-voltage grid monitoring systems, the HAT400-S acts as a robust safety barrier.

Wide Temperature Range for Harsh Environments

The sensor operates stably from -40 ℃ to +105 ℃. Whether in extremely cold outdoor wind power equipment in northern regions or in high-temperature, highhumidity industrial frequency converters running continuously in the south, the HAT400-S maintains its measurement accuracy without drift or reliability loss.

Fast Response to Capture Transient Currents

Response time is less than 5 μs, and the frequency bandwidth covers DC to 25 kHz. From DC steady-state currents to pulsed currents generated under highspeed switching, the HAT400-S captures them in real time without distortion and outputs a ±4 V voltage signal, which can be directly connected to a PLC or monitoring system for real-time analysis and processing. Whether for fault transient identification or high-frequency current waveform monitoring, this sensor rises to the challenge.

Low Power Consumption for Energy Efficiency

Maximum current consumption is only ±15 mA when operating from a ±15 V supply. In modern electronic systems that pursue green energy efficiency and low standby power, the HAT400-S reduces the power burden on the system and effectively lowers overall heat generation and energy consumption, providing significant advantages for energy efficiency targets and thermal design.

Compact Structure for Easy Installation

The sensor has compact dimensions and weighs approximately 300 g, with a 40.5 mm × 30.5 mm aperture for the primary conductor. It supports base mounting and covers a wide current range from 200 A to 1500 A with a single design, greatly simplifying product selection and inventory management. Whether integrated on a PCB, mounted on a DIN rail, or embedded in a complete system, the HAT400-S is easy to accommodate and saves valuable design space.

HAT400-S Typical Applications

Industrial Automation

In PLC control systems, variable frequency drives, and motor servos, the sensor provides real-time monitoring of motor current and drive output current, supplying precise data for overload protection, status diagnosis, and energy efficiency optimisation.

Renewable Energy

Used in solar PV inverters, wind turbine converters, and energy storage systems to track grid-connected current in real time, helping systems operate at their maximum power point and improving energy conversion efficiency.

Electric Vehicles & Battery Management

Applied in on-board chargers (OBCs), battery management systems (BMSs), and motor drive controllers to monitor battery charge/discharge current and motor operating current, ensuring the safety and reliability of electric vehicle systems.

Power Supply Systems

Widely used in uninterruptible power supplies (UPS), switch-mode power supplies (SMPS), and welding power sources to monitor load current in real time, providing reliable support for efficient and stable equipment operation.

Railway Transportation

Performs current detection in locomotive traction systems and on-board energy metering devices, meeting the stringent requirements of railway applications for high reliability, wide temperature operation, and high insulation withstand voltage.

Energy Management Systems

In smart distribution cabinets, energy consumption monitoring terminals, and similar devices, the sensor enables precise power metering and consumption analysis, empowering intelligent energy management.

HAT400-S Technical Specifications

Why Choose the HAT400-S?

High accuracy ±1% – Designed for precise measurement, ensuring reliable control and protection

Wide range ±1200 A – One sensor covers multiple current levels, simplifying selection

High isolation 3000 V – A robust safety barrier meeting the isolation demands of high-voltage power systems

Wide temperature -40 ℃ ~ +105 ℃ – Immune to extreme cold and heat, suitable for all types of harsh industrial environments

Fast response < 5 μs – Captures transient current changes, providing timely signals for fault diagnosis

Low power consumption ±15 mA – Contributes to system energy efficiency and thermal optimisation

Compact and easy to install – Small footprint, low integration barriers

As a global leader in current and voltage measurement, LEM brings decades of deep technical expertise to the HAT400-S, ensuring quality at every stage – from design and production to testing. Each HAT400-S unit is rigorously calibrated and validated for long-term, stable operation in your system.

Whether you are developing next-generation industrial power supplies, electric vehicle control systems, or upgrading smart grid equipment, the HAT400-S is a current measurement partner you can trust.