Current Sense Transformers

Part Number	Description / PDF	Quantity
B82801B0925A200 TDK EPCOS	CURR SENSE XFMR 1:200 20A SMD	451
B82801B0504A050 TDK EPCOS	CURR SENSE XFMR 1:50 SMD	145
B78419A2290A003 TDK EPCOS	CURR SENSE XFMR 1:125 SMD	199
B78417A2285A003 TDK EPCOS	CURR SENSE XFMR 1:50 SMD	590
B82801A1304A060 TDK EPCOS	EE4.2 SMD TRANSFORMER_P301767	600
B82801A1404A070 TDK EPCOS	EE4.2 SMD TRANSFORMER_P301768	600
B82801A1134A040 TDK EPCOS	EE4.2 SMD TRANSFORMER_P301765	600
B82801A1824A100 TDK EPCOS	CURR SENSE XFMR 1:100 SMD	14955
B78419A2289A003 TDK EPCOS	CURR SENSE XFMR 1:70 SMD	79
B82801C1265A150 TDK EPCOS	CURR SENSE XFMR 1:150 SMD	182
B78417A2287A003 TDK EPCOS	CURR SENSE XFMR 1:125 SMD	120
B82801A1743A 30 TDK EPCOS	CURR SENSE XFMR 1:30 SMD	0
B82801A2824A100 TDK EPCOS	CURR SENSE XFMR 1:100 SMD	0
B82801A0134A040 TDK EPCOS	CURR SENSE XFMR 1:40 SMD	0
B82801A0214A050 TDK EPCOS	CURR SENSE XFMR 1:50 SMD	0
B82801A0824A100 TDK EPCOS	CURR SENSE XFMR 1:100 SMD	0
B82801A0304A060 TDK EPCOS	CURR SENSE XFMR 1:60 SMD	0
B82801A0404A070 TDK EPCOS	CURR SENSE XFMR 1:70 7A SMD	0
B82801A0743A030 TDK EPCOS	CURR SENSE XFMR 1:30 SMD	0
B82801A0135A125 TDK EPCOS	CURR SENSE XFMR 1:125 SMD	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.