Current Sense Transformers

Part Number	Description / PDF	Quantity
CT-0400-D20 Wickmann / Littelfuse	CURR SENSE XFMR 400:5 DONUT	1
CR5RL-500 CR Magnetics, Inc.	CURR SENSE XFMR 50A IN-LINE	0
CR8350-2000-D CR Magnetics, Inc.	CURR SENSE XFMR 100A T/H	0
AS-406 Amgis	XFRMR CURR 65A 1:500 VRT	0
2277857 Phoenix Contact	CURR SENSE XFMR 200A DIN RAIL	0
CR8449-2000 CR Magnetics, Inc.	CURR SENSE XFMR 75A IN-LINE	0
CR6ARL-301 CR Magnetics, Inc.	CURR SENSE XFMR 300A IN-LINE	0
AS-330 Amgis	XFRMR CURR 15A 1:50CT VRT	0
CR2RL-201 CR Magnetics, Inc.	CURR SENSE XFMR 200A	0
CTG160 Carlo Gavazzi	CORE BALANCE TRANSFORM 0160MM	0
CR5RL-501 CR Magnetics, Inc.	CURR SENSE XFMR 500A IN-LINE	0
A82-2025 Carlo Gavazzi	1PH CURR XFMR 4-20MA OUTPUT	0
ZSCT5-88 Wickmann / Littelfuse	CT 100:1 NO FLUX COND 88MM	0
2277200 Phoenix Contact	CURR SENSE XFMR 1:250 1250A DIN	0
AS-110 Amgis	XFRMR CURR 15A 1:50CT VRT	0
AS-302 Amgis	XFRMR CURR 15A 1:200 VRT	0
CR8450-2000 CR Magnetics, Inc.	CURR SENSE XFMR 200A IN-LINE	0
2277611 Phoenix Contact	CURR SENSE XFMR 75A DIN RAIL	0
2277145 Phoenix Contact	CURR SENSE XFMR 1:160 800A DIN	0
A82-10500 Carlo Gavazzi	1PH CURR XFMR 0-20MA OUTPUT	0

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.