SMD Mount current transformer ACSTER11.5 Series for High Accuracy Current Sensing

Introduction

In modern power electronics systems, accurate current sensing is essential for safe operation, energy monitoring, and system protection.

As power density continues to increase in EV charging systems, industrial automation equipment, and switching power supplies, designers are often forced to measure high current in extremely compact PCB spaces.

Traditional current sensing methods struggle with three major limitations:

• Insufficient isolation under high voltage conditions
• Magnetic saturation at high current levels
• Poor integration in compact SMD-based designs

The ACSTER11.5 series SMD current Transformer is designed specifically to solve these challenges by combining high current sensing capability with reinforced insulation and compact surface-mount structure.

Porduct Overview

The ACSTER11.5 series is a surface-mount current transformer designed for accurate AC current measurement in high-density electronic systems.

It provides electrical isolation between primary and secondary circuits while converting high primary current into a measurable secondary signal.

This series is widely used in:

• Industrial power monitoring systems
• EV charging infrastructure
• Switching power supplies (SMPS)
• Energy metering equipment
• High-frequency power conversion systems

Key Features

High Current Sensing Capability up to 50A

• The ACSTER11.5 series supports sensing currents up to 50A, making it suitable for medium-to-high power industrial applications where stable current feedback is required under dynamic load conditions.

Very Low DC Resistance for High Efficiency

• With extremely low DC resistance of approximately 0.56 mΩ, power loss inside the sensing loop is minimized, improving measurement stability and reducing thermal drift in continuous operation.

Compact SMD Mount Design

• The surface-mount structure enables direct PCB integration, reducing assembly complexity and improving suitability for automated manufacturing in compact power systems.
• Package dimensions are optimized for high-density layouts where space is limited.

High Isolation Voltage (Up to 5000VDC)

• The ACSTER11.5 series provides reinforced insulation with 5kV DC isolation (6 seconds test condition), ensuring safe operation between high-voltage primary circuits and low-voltage control systems.
• This makes it suitable for EV charging and industrial power environments where safety compliance is critical.

Engineering Performance Notes

In real-world applications, current transformer performance is influenced not only by rated current, but also by:

• Turns ratio selection
• Core linearity under transient load
• PCB layout parasitic effects
• Thermal rise under continuous operation
• Frequency-dependent loss behavior

During evaluation of compact EV charging and industrial monitoring systems, improper CT selection often leads to:

• Signal distortion at peak load
• Measurement drift under temperature rise
• Reduced accuracy during fast load transitions

For this reason, designers typically prioritize saturation behavior and insulation strength over nominal inductance values.

Technical Specifications

Applications

EV Charging Systems

• Used for real-time current monitoring in high-power charging circuits where safety isolation and accuracy are critical.

Industrial Power Monitoring

• Provides stable current feedback for energy measurement, load balancing, and system protection in industrial distribution systems.

Switching Power Supplies (SMPS)

• Supports high-frequency current sensing in compact DC-DC and AC-DC Converter systems.

Energy Metering Systems

• Used in smart metering applications requiring accurate current conversion and long-term stability.

High-Density PCB Power Electronics

• Ideal for compact designs where traditional through-hole current Transformers cannot be integrated.

FAQ

What is the main advantage of SMD current transformers?

• SMD current transformers allow direct PCB integration while maintaining electrical isolation and accurate current sensing in compact systems.

Why is 5000V isolation important?

• High isolation voltage ensures safe separation between high-voltage power circuits and low-voltage control systems, especially in EV and industrial applications.

Can this CT be used in high-frequency switching systems?

• Yes, the ACSTER11.5 series supports operation up to 1MHz, making it suitable for modern switching power supplies and high-frequency converters.

What happens if current exceeds rated limits?

• Excessive current may lead to core saturation, causing measurement distortion and reduced accuracy in output signals.

About FERRTX Engineering Team