Precision AC Current Sensing & Isolation Engineering
Current sense transformers detect alternating electrical currents (AC), measure current levels precisely based on electromagnetic induction, and step down large currents into proportional, manageable output signals for control circuits, metering equipment, and protective relays.
Unlike resistive sensing methods that generate unwanted heat and power losses, current sense transformers utilize low-loss magnetic cores to provide essential safety isolation. By separating high-voltage primary circuits from sensitive control electronics, current sense transformers safeguard delicate microcontrollers, feedback systems, and human operators against electrical transients.
Triad Magnetics current sense transformers draw negligible power from the primary conductor. For applications requiring precise threshold detection, our magnetic components deliver linear output voltages ideal for triggering automated safety shut-offs, fault logging, and system diagnostics.
Standard & Custom Current Sense Transformer Product Lines
Triad Magnetics engineers and manufactures five comprehensive standard current sense transformer series designed for surface-mount (SMT) and through-hole PCB assembly. All standard models comply with RoHS 2015/863/EU directives and utilize UL Class 130 (B) insulation systems.
1. CST206 / CST306 Series – High-Frequency Current Sensing
Engineered for switch-mode power supply (SMPS) applications operating between 20 kHz and 200 kHz. Built with high-permeability ferrite cores to measure primary currents accurately with minimal phase distortion.
- Operating Frequency: 20 kHz to 200 kHz
- Construction: Through-hole casting with optional center-tap configuration
- Thermal Rating: UL Class 130 ºC (B) insulation; 40 °C temperature rise at rated current
- Recommended Terminating Resistance: 1 ohm per turn maximum
2. CSE5 Series – Surface Mount (SMT) High-Frequency Current Transformers
Designed specifically for automated surface-mount pickup and placement in high-density power electronics operating at 250 kHz and above.
- Primary Current Rating: 10 Amps continuous
- Operating Frequency: 250 kHz and higher
- Operating Temperature Range: -15 °C to +105 °C
- Target Applications: Switch-mode power feedback, DC-DC converters, LED driver output control
3. CSE Series – Low-Frequency Current Transformers
Optimized for low-frequency AC current detection in industrial process controls and power distribution networks requiring high reliability under continuous operation.
- Insulation Rating: Recognized Component Class 130 (B) system (OBJY2), designated B3
- Mounting: Rugged PCB through-hole pin termination
- Key Benefit: High linear measurement precision for energy management systems
4. CST Series – 50Hz / 60Hz Low-Frequency Current Sensing
Built for utility line-frequency monitoring applications operating at 50 Hz or 60 Hz. Designed with robust potting compounds for harsh environmental conditions.
- Operating Frequency: 50 Hz / 60 Hz mains power
- Mechanical Features: Dedicated mechanical support pin (0.8±0.1 mm diameter, 5±1 mm length)
- Dielectric Isolation: High voltage breakdown resistance between primary and secondary circuits
5. CST25 Series – High-Isolation Switch-Mode Current Sensors
Encapsulated current sense transformers providing maximum electrical safety isolation up to 4000 VAC between primary and secondary windings.
- Isolation Breakdown Rating: 4000 VAC primary-to-secondary
- Standard Turns Ratios: 1:50, 1:100, 1:200, and 1:500
- Applications: Medical electronics, industrial automation, commercial lighting power supplies
Technical Specifications Comparison
Review standard current sense transformer series characteristics to match your OEM application requirements:
| Series | Frequency Range | Primary Current | Turns Ratios | Mounting Type | Insulation Class |
|---|---|---|---|---|---|
| CST206 / CST306 | 20 kHz – 200 kHz | Up to 80A peak | 1:50, 1:100, 1:200, 1:300 | Through-Hole | Class 130 (B) |
| CSE5 Series | 250 kHz+ | 10A max | 1:50, 1:100, 1:200 | Surface Mount (SMT) | Class 130 (B) |
| CSE Series | 50 Hz – 400 Hz | 5A – 30A | 1:500, 1:1000 | Through-Hole | Class 130 (B) OBJY2 |
| CST Series | 50 Hz / 60 Hz | 10A – 50A | 1:500, 1:1000 | Through-Hole | Class 130 (B) |
| CST25 Series | 20 kHz – 200 kHz | Up to 40A | 1:50, 1:100, 1:200, 1:500 | Encapsulated PCB | 4000 VAC Isolation |
Custom Design & OEM Engineering Support
When standard off-the-shelf magnetics do not meet your exact mechanical footprint, pinout, turns ratio, or dielectric requirements, Triad Magnetics’ U.S. Design Center delivers complete custom current sense transformer engineering services.
Our ISO 9001:2015 certified engineering team supports global OEM buyers through every design stage:
- Rapid Prototyping & Testing: Advanced magnetic modeling, thermal analysis, and fast prototype turnaround.
- Regulatory Compliance Assistance: Design verification to UL, CSA, CE, IEC 60601-1 (medical), and RoHS standards.
- Dual-Sourcing Security: State-of-the-art manufacturing facilities in the United States and the Philippines ensure flexible capacity and uninterrupted supply chain delivery.
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