LT 4000-S/SP22 – 4,000A Closed-Loop Hall Effect Current Transducer

LT4000-S/SP22 Product Overview

In today’s fast-moving world of power electronics, accurate current monitoring and control is the foundation of system safety and operational efficiency. The LT 4000-S/SP22 closed-loop Hall effect current transducer from LEM combines excellent precision, fast dynamic response, and a rugged mechanical design, making it ideal for high-power industrial applications and railway traction systems.

With a rated current of 4,000A and a measuring range up to ±6,000A, the LT 4000-S/SP22 easily handles demanding scenarios such as high-power variable frequency drives, DC motor controls, UPS systems, and welding power supplies. Whether measuring DC, AC, or pulse currents, the transducer provides accurate, galvanically isolated measurements – becoming a reliable choice for power electronics engineers.

LT4000-S/SP22 Key Technical Highlights

The LT 4000-S/SP22 uses closed-loop Hall effect technology – a proven, high-precision method for current sensing. In a closed-loop design, the secondary coil generates a compensation magnetic field that dynamically cancels the primary current’s magnetic field, achieving excellent linearity and stability over a wide measuring range. Its performance advantages include:

Outstanding measurement accuracy – Overall accuracy up to ±0.5% and linearity better than 0.1%, providing highly reliable current data for high-power systems.

Extremely fast dynamic response – Response time less than 1 µs, capable of accurately tracking current slew rates up to 50 A/µs, even for fast-transient pulse currents.

Wide frequency range – Bandwidth from DC to 100 kHz, covering DC through high-frequency AC applications.

Excellent temperature stability – Offset current thermal drift better than ±0.8 mA over the operating temperature range (-25°C to +70°C), ensuring consistent measurement accuracy under varying conditions.

High immunity to interference – Excellent rejection of external stray magnetic fields, ensuring reliable operation in complex power electronics environments.

Current overload capability – Withstands transient overcurrents while maintaining measurement safety.

Galvanic isolation – 6 kV RMS isolation voltage (50 Hz, 1 minute) between primary and secondary circuits. The insulated plastic case meets UL 94-V0 flame retardancy, guaranteeing absolute safety between high-voltage and lowvoltage electronic circuits.

LT4000-S/SP22 Product Specifications

LT4000-S/SP22 Industry Applications

With its high accuracy, high current rating, and fast response, the LT 4000-S/SP22 plays an essential role in several key industries:Industrial drives – AC variable frequency drives and servo motor drives are core applications. In highperformance motor control systems, accurate current feedback is essential for precise torque control and efficiency optimisation – especially in industrial robots, cranes, and elevators.

DC motor drives – In static converter systems for DC motor drives, the transducer provides realtime monitoring of highpower DC bus currents for system protection and closed-loop control.

Power supplies – UPS and switchedmode power supplies rely on accurate current detection to ensure stable output voltage and overload protection.

Welding equipment – In welding power sources, the transducer precisely captures complex welding current waveforms for highquality weld control.

Renewable energy – Wind turbines, solar inverters, and other renewable energy systems require accurate highcurrent monitoring for energy conversion and gridtie control.

Railway & traction – The LT series is widely used in train, locomotive, and metro vehicle traction inverters, drive/brake choppers, auxiliary converters, and other critical systems, ensuring safe and efficient railway operation.

LT4000-S/SP22 Installation and Design Advantages

The LT 4000-S/SP22 uses a panel-mount design for straightforward installation. It features a 102 mm diameter through-hole for easy insertion of large primary conductors without cutting or disconnecting existing cables – especially suitable for high-current busbars.

With a rugged 6 kg construction and wide operating temperature range (-25°C to +70°C), the transducer delivers long-term reliability even in harsh industrial environments.