Current Sense Transformers

Part Number	Description / PDF	Quantity
CST-1030 Triad Magnetics	CURR SENSE XFMR 30A T/H	11221796
PA1005.125NL PulseLarsen Antenna	CURR SENSE XFMR 1:125 20A SMD	2001
CR2SFT-101 CR Magnetics, Inc.	CURR SENSE XFMR 100A T/H	18
53100C Murata Power Solutions	CURR SENSE XFMR 1:100 10A SMD	484
CT250A Hammond Manufacturing	CURR SENSE XFMR 5A CHAS MNT	7
CR8450-1000 CR Magnetics, Inc.	CURR SENSE XFMR 100A IN-LINE	1821
B82801A1333A020 TDK EPCOS	CURR SENSE XFMR 1:20 SMD	1357
CST306-2T-B Triad Magnetics	CURR SENSE XFMR 25A T/H	720
PB0027NL PulseLarsen Antenna	CURR SENSE XFMR 200:1 35A SMD	608
CST306-1A-B Triad Magnetics	CURR SENSE XFMR 35A T/H	6480
CT-0200-D20 Wickmann / Littelfuse	CURR SENSE XFMR 200:5 DONUT	0
CST206-3A Triad Magnetics	CURR SENSE XFMR 70A T/H	1400901
56300C Murata Power Solutions	CURR SENSE XFMR 10A T/H	3
749252030 Würth Elektronik Midcom	WE-CST CURRENT SENSE TRANSFORMER	1994
B78419A2251A003 TDK EPCOS	CURR SENSE XFMR 1:100 SMD	858
PE-67100NL PulseLarsen Antenna	CURR SENSE XFMR 37A T/H	0
CT-1020 Amgis	CURR SENSE XFMR 20A T/H	0
CR3111-3000 CR Magnetics, Inc.	CURR SENSE XFMR 100A IN-LINE	105
CT-1025 Amgis	CURR SENSE XFMR 25A T/H	279
B82801A1214A050 TDK EPCOS	EE4.2 SMD TRANSFORMER_P301766	559

Current Sense Transformers

1. Overview

Current Sense Transformers (CSTs) are specialized electromagnetic devices designed to accurately detect and measure alternating current (AC) in electrical circuits. By converting primary current signals into proportional secondary currents or voltages, CSTs enable safe and reliable monitoring for control systems, energy management, and protection circuits. Their importance in modern technology spans power electronics, industrial automation, renewable energy systems, and smart grid infrastructure, where precise current measurement is critical for efficiency optimization and system safety.

2. Main Types and Functional Classification

Type	Functional Features	Application Examples
Open-Circuit Core CST	Low cost, wide current range, moderate accuracy	Smart meters, household appliances
Closed-Loop Core CST	High accuracy (0.1%~0.5%), low phase error	Motor drives, precision power supplies
Hall Effect Integration	DC/AC hybrid measurement, galvanic isolation	Electric vehicle BMS, energy storage systems
High-Frequency CST	Operates >100kHz, minimized core loss	Wireless charging systems, induction heating
Miniature Surface-Mount	Compact size, PCB-mountable	Consumer electronics, IoT devices

3. Structure and Components

Typical CST construction includes: - Magnetic Core: Made from ferrite, silicon steel, or nanocrystalline materials to ensure high permeability and low loss - Primary Winding: Single-turn or multi-turn conductor depending on current range - Secondary Winding: Multi-turn coil with precise turns ratio for signal scaling - Insulation System: Epoxy resin or plastic housing meeting UL/IEC dielectric standards - Termination: Screw terminals, PCB pins, or integrated connectors Advanced models incorporate shielding layers and temperature-compensated materials for enhanced stability.

4. Key Technical Specifications

Parameter	Typical Range	Significance
Current Ratio	100:1 to 5000:1	Determines scaling factor for measurement
Accuracy Class	0.1% to 1%	Critical for metering and control precision
Frequency Range	50Hz-1MHz	Dictates application suitability
Phase Shift	<1	Affects power factor calculation accuracy
Isolation Voltage	2.5kV-10kV	Ensures safety in high-voltage systems
Operating Temp.	-40 C to +125 C	Environmental reliability indicator

5. Application Fields

Major industries and equipment utilizing CSTs include:

Energy Sector: Smart grids, substation protection relays
Industrial Automation: Variable frequency drives, PLC systems
Renewable Energy: Solar inverters, wind turbine converters
Transportation: EV charging stations, traction control systems
Consumer Electronics: Smart home appliances, power banks

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Features
ABB	ACS711	2kV isolation, 1% accuracy for EV charging
LEM	HASS 25-S	Open-loop sensor with 120A measurement range
TE Connectivity	CurrentSense 55512	Surface-mount design for PCB integration
Vacuumschmelze	DIN43858	High-frequency capability up to 500kHz
Allegro Micro	ACS37610	Digital output with I C interface

7. Selection Guidelines

Key considerations for CST selection:

Required current ratio and measurement range
Accuracy demands (metering vs. protection applications)
Environmental conditions (temperature, humidity, vibration)
Frequency characteristics of the target circuit
Space constraints and mounting requirements
Cost-performance balance for mass production

Example: For PV inverter applications, select a closed-loop core CST with >200kHz bandwidth and IP67 rating to ensure reliable operation under fluctuating environmental conditions.

8. Industry Trends

Emerging trends shaping CST development include:

Integration with digital interfaces (CAN, Modbus) for smart systems
Wide bandgap semiconductor compatibility (SiC/GaN circuits)
Nano-material core adoption for reduced size and weight
AI-enhanced error compensation algorithms
Increased adoption in EV infrastructure and energy storage systems

Market forecasts indicate 8.2% CAGR through 2030, driven by renewable energy integration and industrial IoT expansion.