CKSR25-NP High-Precision Fluxgate Current Transducer

CKSR25-NP Product Overview

In modern power electronics, high efficiency and reliability start with accurate current sensing. The LEM CKSR25-NP is a closed-loop fluxgate current transducer designed for precise measurement of DC, AC, and pulsed currents, with galvanic isolation between primary and secondary circuits.

Rated for 25A primary current (expandable to ±85A peak), it provides a sensitivity of 25mV/A, accuracy of ±0.8% and a fast response time of just 0.3µs. The CKSR25-NP perfectly balances high accuracy, fast response, and compact size. It is ideal for variable frequency drives, servo motors, UPS, PV inverters, and switch-mode power supplies — a core sensing component in industrial automation and renewable energy systems.

Why choose CKSR25-NP?

Flexible measuring range — Multi-range design: by wiring the primary pins in series or parallel, you can select rated currents of 25A, 12.5A, or 8.33A, increasing resolution up to 3× for low-current applications.

 ±0.8% accuracy, 300kHz bandwidth — Closed-loop fluxgate technology delivers excellent linearity, low temperature drift, and high-frequency response comparable to high-end Hall-effect transducers, suitable for IGBT/SiC high-frequency switching current measurement.

4.75V~5.25V single supply, PCB through-hole mounting — Compact, board-level design that is footprint-compatible with the LTS series for easy drop-in upgrades with minimal board rework.

-40℃ to +105℃ wide temperature range, 1000Vrms isolation — Built for harsh industrial environments with safe galvanic isolation.

UL 94-V0 flame rating, RoHS & CE compliant — Safe and environmentally friendly, supporting green manufacturing.

CKSR25-NP Key Technical Specifications

CKSR25-NP Key Features

Fluxgate technology for superior accuracy

The CKSR25-NP uses closed-loop fluxgate technology, offering much lower offset drift, better dv/dt immunity, and higher creepage distance than open-loop Hall sensors — significantly improving measurement accuracy and system stability. As a global leader in electrical measurement, LEM’s CKSR series is optimised for advanced drive and inverter applications, excelling in common-mode rejection, thermal drift, response time, insulation, and size.

Multi-range design – one part for multiple needs

Three primary pins allow easy range switching by changing the wiring configuration. Parallel connection gives the full 25A rating; series connection reduces the range to 1/3 (approx. 8.33A) while tripling resolution. This flexibility reduces part numbers and inventory costs.

Compact size, easy upgrade

With a height of only 16.5mm (about 30% lower than traditional LTS series), the CKSR25-NP is footprint-compatible with LTS / LTSR series – a drop-in replacement without PCB redesign.

Wide-temperature stability for harsh environments

Operates reliably from -40℃ to +105℃ with low temperature drift, maintaining high accuracy across the full range – whether in freezing outdoor conditions or hot industrial sites.

CKSR25-NP Typical Applications
Variable frequency drives & servo motor control – Phase current sensing in AC drives and servo systems for precise closedloop control and fast response.

Photovoltaic inverters & renewable energy – MPPT tracking and grid current measurement in solar inverters, ensuring high-efficiency operation.

Uninterruptible power supplies (UPS) & switch-mode power supplies (SMPS) – Current monitoring and control to guarantee stable output and protection.

DC motor drives & static converters – Accurate current measurement for efficient speed regulation and overcurrent protection.

Battery management systems (BMS) – Charge/discharge current monitoring in battery-powered equipment.

Industrial automation & home appliances – Current sensing in high-precision robot servo drives, air conditioners, and other appliances.

Welding power supplies – Precise current control for improved weld quality and process stability.

Smart grid & power quality monitoring – Real-time AC/DC current measurement for energy monitoring and optimisation.