CASR 25-NP/SP3 Closed-Loop Fluxgate Current Sensor

CASR25-NP/SP3 Product Overview

The CASR 25-NP/SP3 is a high-performance closed-loop fluxgate current sensor from LEM, the world leader in current sensing technology. Part of the CASR-NP series, this sensor is specifically designed to support the technological advancement of drives and inverters in industrial environments, delivering outstanding performance in accuracy, response time, thermal stability, insulation, and compact dimensions.

Leveraging advanced closed-loop fluxgate technology, the CASR 25-NP/SP3 provides high-accuracy, high-resolution isolated measurement of DC, AC, and pulsed currents. It operates from a single +5 V supply, features PCB-mount through-hole installation, offers a rated current of 25 A, and can measure up to 85 A peak.

Whether you are designing industrial variable-frequency drives, servo drives, robotic control systems, or test & measurement equipment that demands high-precision current detection, the CASR 25-NP/SP3 delivers a reliable, accurate current-sensing solution that you can trust.

CASR25-NP/SP3 Key Advantages

Closed-Loop Fluxgate Technology – Accuracy Without Compromise

Unlike conventional Hall-effect sensors, the CASR 25-NP/SP3 employs LEM’s proprietary closed-loop fluxgate technology, enabling high-accuracy current measurement over a wide frequency range (DC to 300 kHz). Its output signal is an accurate, high-resolution reproduction of the primary current with extremely low delay, performing exceptionally well even at high frequencies – comparable to traditional current transformers. With ±0.8% accuracy and ±0.1% linearity, your measurement data is reliable and trustworthy.

300 ns Ultra-Fast Response – Capture Transient Changes Instantly

Response speed is a critical differentiator for current sensors. The CASR 25-NP/SP3 offers a 300 ns response time, enabling it to quickly capture transient current changes and provide real-time, precise feedback to your control system. This makes it especially suitable for drive and inverter applications that require demanding dynamic performance.

Wide Temperature Range – Stable Performance in Harsh Environments

From extreme cold to high heat, the CASR 25-NP/SP3 maintains consistent performance. Its -40 °C to +105 °C operating temperature range allows it to thrive in the most challenging industrial conditions. The sensor also excels in commonmode rejection and thermal drift (offset and gain), ensuring reliable operation even in high-humidity, high-temperature environments.

Galvanic Isolation – High-Voltage Safety Assured

The CASR 25-NP/SP3 provides safe galvanic isolation between the primary and secondary circuits, with a rated insulation voltage of 1000 Vrms. This feature allows you to integrate it into highvoltage systems with complete confidence, free from safety concerns.

Compact Design – Flexible Installation

Featuring a compact PCB-mount design, the sensor’s height is reduced by 30% compared to the LTS series. The housing incorporates three U-shaped primary terminals for easy PCB layout. The insulating plastic case meets UL 94-V0 flammability rating, combining safety with reliability. Each unit weighs only about 10.6 g, occupying minimal board space.

CASR25-NP/SP3 Technical Specifications

CASR25-NP/SP3 Typical Applications

Industrial Variable-Frequency Drives & Servo Drives – providing precise current feedback for motor control

Robotic Control Systems – meeting demanding requirements for high dynamic response and reliability

Test & Measurement Equipment – delivering high-accuracy, high-resolution current detection

Power Supply Management & Monitoring – real-time monitoring of power supply current status

Automotive Electronics – suitable for on-board current detection applications

Why Choose the CASR 25-NP/SP3?

As the global leader in current sensing, LEM’s CASR series leverages advanced fluxgate technology to improve accuracy while effectively controlling cost – an ideal alternative to traditional Hall-effect sensors.