CTSR1-TP/SP19 High-Accuracy Closed-Loop Fluxgate Current Sensor

CTSR1-TP/SP19 Product Overview

The CTSR1-TP/SP19 is a high-precision miniature current sensor from LEM’s CTSR series, built on advanced closed-loop fluxgate technology. It is specifically designed for residual current measurement and low-current detection applications. As a world leader in current sensing, LEM sets the industry benchmark for reliability and accuracy. With its non-contact measurement, compact PCB-mount design, and excellent temperature drift suppression, the CTSR1-TP/SP19 delivers precise current monitoring for industrial power supplies, photovoltaic inverters, uninterruptible power supplies, and more.

CTSR1-TP/SP19 Key Performance Specifications

CTSR1-TP/SP19 Core Advantages

Precision Low-Current Measurement

Optimised for milliampere-level currents, the CTSR1-TP/SP19 reliably measures small currents from 0.3 Aᵣₘₛ up to 1.7 A. Whether for residual current detection or fault monitoring, it provides stable, trustworthy data.

Safe, Non-Contact Sensing

The large aperture (Ø 20.1 mm) accommodates a plugin conductor, enabling true non-contact measurement. This enhances safety and simplifies installation and maintenance.

Exceptional Temperature Stability

With a wide operating range of -40 °C to +105 °C and low offset drift, the sensor maintains stable output even in harsh industrial environments. An auxiliary reference voltage pin helps eliminate A/D converter temperature drift, further improving system-level accuracy.

Fast Response & Wide Bandwidth

A 30 µs response time and DC-9.5 kHz bandwidth allow accurate capture of DC, AC, and pulsed signals, meeting the demands of dynamic current detection.

Plug-and-Play Design

Single +5 V supply and output directly compatible with 5 V inputs of microcontrollers and instrumentation boards. The included plug-in lead (TP version) enables quick installation without extra tools.

CTSR1-TP/SP19 Typical Applications

Photovoltaic inverters – ground leakage detection and personnel protection

Uninterruptible power supplies (UPS) – fault detection and current monitoring

Switched-mode power supplies – current monitoring and protection

Industrial power supplies and converters – symmetrical fault detection

Residual current monitoring (RCD) – ground leakage detection in single-phase and threephase systems

CTSR1-TP/SP19 Technical Highlights

Closed-Loop Fluxgate Technology – Compared to traditional open-loop Hall sensors, closed-loop fluxgate offers higher accuracy, lower temperature drift, and better linearity. The insulation test voltage is 5.4 kVᵣₘₛ / 50 Hz / 1 min, with creepage and clearance distances of 11 mm, ensuring excellent insulation performance.

Flexible Reference Voltage – An additional output pin provides an internal reference voltage, or it can accept an external reference (2.3~4 V) from a DSP or A/D converter, effectively eliminating system-level temperature drift errors.

Built-in Self-Test & Demagnetisation – Integrated self-test and demagnetisation functions guarantee long-term reliability and measurement accuracy.

Why Choose the CTSR1-TP/SP19?

Choose the CTSR1-TP/SP19 and benefit from LEM’s 30+ years of sensor development expertise – precision, reliability, and durability make it the ideal choice for your current sensing needs.