FL 28000-SD Series: An Innovative Choice for Industrial-Grade Large Current Detection
1. One-Sentence Description
The FL 28000-SD series is a high-precision, wide-range open-loop current sensor based on Hall effect, specially designed to provide electrical isolation solutions for large current detection in industrial and rail transit fields.
2. Core Features
- Open-loop coreless design with Hall effect: Adopts coreless architecture (OLCI technology) to eliminate hysteresis and magnetic offset interference.
- Ultra-wide range coverage: Supports 0-42kA for unipolar and ±42kA for bipolar, adapting to extreme working conditions.
- High isolation performance: Meets standards like IEC 61800-5-1, with 44kV (impulse) withstand voltage between primary/secondary circuits.
- Flexible output and power supply: 0-5V linear voltage output, supports 12V/24V DC power supply, with power consumption as low as 100mA (24V).
- Factory precision calibration: Pre-calibrated to ensure high linearity (total error ±0.65% @25℃).
- Environmental adaptability: Operating temperature -40℃~+85℃, dustproof and waterproof design (UL 94 VO flame-retardant housing).
3. Core Technical Specifications
| Parameter | Typical Value | Limit Value |
|---|---|---|
| Measurement Range | ±28kA (FL 28000) | ±42kA (FL 28000) |
| Sensitivity | 0.048~0.095 mV/A | — |
| Bandwidth | 100 kHz (-3dB) | — |
| Response Time | ≤4 μs (@100A/μs) | — |
| Insulation Strength | Power frequency withstand voltage 12kV/1min | Impulse withstand voltage 44kV |
| Power Consumption | 100~240 mA | — |
4. The Story Behind the Chip
The FL 28000-SD series was born in the context of rapid development in new energy and industrial automation. With the surging demand for high-power power conversion in wind power, high-speed rail, electric vehicles and other fields, traditional current transformers are difficult to meet the requirements due to large size, easy saturation, and poor dynamic response. Relying on its technical accumulation in the magnetic sensing field, LEM innovatively integrated coreless Hall effect technology with high-reliability packaging technology to overcome the problems of signal distortion and thermal management under large currents, and launched a new generation of sensors with both high precision and strong environmental adaptability.
5. Design Philosophy
- Minimalist architecture: Abandons traditional iron cores, achieving zero magnetic offset through closed-loop algorithm compensation for magnetic field distortion.
- Modular design: Supports two busbar sizes of 200mm×100mm and 300mm×100mm, compatible with rectangular and circular conductors.
- Safety redundancy: Dual insulation protection (reinforced insulation + creepage distance >100mm), compliant with rail transit EN 50155 vibration standards.
- Intelligent compatibility: M12 connector integrated with shielding layer, supporting digital interface expansion (requires matching with LEM special IC).
6. Application Scenarios
- New energy field: Photovoltaic inverters, wind power converters (monitoring DC bus current).
- Industrial drive: High-voltage frequency converters, servo motor control (real-time feedback current loop).
- Rail transit: Traction converters, auxiliary power systems (complying with IEC 61992-7 railway standards).
- Power grid facilities: DC circuit breaker testing, harmonic filter monitoring (supporting 100kHz high-frequency signal capture).
7. Unique Advantages
- Zero hysteresis and self-calibration: Coreless design completely eliminates remanence influence, improving long-term stability by 50%.
- Anti-interference leader: Built-in EMI filter circuit, 60dB noise suppression at 100kHz.
- Ultra-fast response: 4μs step response, easily coping with IGBT high-frequency switching scenarios.
- Extreme lightweight: Only 1.177kg (SD200 model), 60% lighter than traditional sensors.
- Full lifecycle reliability: Passed 1000-hour aging test at 85℃/85% humidity, with reversible drift.
8. Key Considerations for Engineers in Selection
- Precise current level matching: Select models at 120% of the actual peak current (e.g., FL 28000 for 30kA systems).
- Power supply voltage adaptation: Higher accuracy at 24V power supply, but ensure line voltage drop <0.5V.
- Installation spacing specification: Primary busbar edge to sensor inner wall ≥3mm to avoid edge effect errors.
- Environmental stress verification: Additional evaluation of junction temperature (max 105℃) and material aging risks in hot and humid areas.
- Certification compliance: Rail transit projects require UL 61010-1 certified versions, while new energy fields focus on IEC 62477-1 CAT IV rating.
- Cost trade-off: Although the unit price is higher than traditional transformers, maintenance-free features can reduce 3-year TCO (total cost of ownership) by over 20%.
Conclusion
The FL 28000-SD series redefines the large current detection standard with its disruptive design, and its characteristics of "zero magnetic offset, high bandwidth, and full sealing" make it a core device for new energy grid connection and smart grid upgrading. Engineers should focus on temperature gradient, mechanical vibration, and electromagnetic compatibility of actual working conditions during selection to fully leverage its performance advantages.
