LF505-S/SP25；LF 505-S/SP25

‌LF505-S/SP25 Product Description: The Trusted Standard in Industrial Current Sensing

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LF505-S/SP25 ‌Product Overview‌
The LF505-S/SP25 is a closed-loop Hall effect current transducer from LEM, engineered for high-precision measurement of DC, AC, and pulsed currents in demanding industrial applications. Leveraging magnetic flux compensation technology, it delivers galvanic isolation between the primary high-current circuit and the secondary control circuit, producing a linear, proportional current output without direct electrical contact. As a mature, field-proven variant within the LF505-S series, the SP25 offers identical performance to the SP28 model, making it the ideal replacement for legacy open-loop sensors or aging units—without requiring redesign, requalification, or firmware updates.

LF505-S/SP25 ‌Key Features‌

‌Closed-Loop Accuracy‌: Achieves ±0.6% overall accuracy and <0.1% linearity through magnetic balance technology, eliminating zero drift and temperature-induced errors for maintenance-free, long-term operation.

‌Microsecond Response‌: ≤1 µs response time enables real-time capture of current transients and high-frequency pulses, critical for dynamic control in servo drives, fast-switching SMPS, and regenerative braking systems.

‌Full Bandwidth Coverage‌: Measures from DC to 100 kHz, accommodating complex waveforms from DC bus lines to high-frequency inverters in modern power electronics.

‌Bidirectional Current Sensing‌: Simultaneously detects positive and negative current flow without external polarity switching circuits, enabling energy recovery, battery charge/discharge monitoring, and motor regeneration control.

‌Industrial Environmental Resilience‌: Encased in UL94V-0 flame-retardant engineering plastic, it operates reliably across a wide temperature range of -40°C to +85°C, withstanding harsh vibration, thermal cycling, and electromagnetic interference.

‌Zero Insertion Loss‌: The closed-loop architecture prevents core saturation, resulting in near-zero series impedance that minimizes power loss and thermal impact on the measured circuit.

LF505-S/SP25 ‌Technical Specifications‌

‌Rated Current‌: 500 A RMS

‌Measurement Range‌: 0 to ±1200 A

‌Supply Voltage‌: ±24 V (range: 24 V ±7% / -5%)

‌Output Type‌: Proportional current output (100 mA full scale)

‌Response Time‌: ≤1 µs

‌Operating Temperature‌: -40°C to +85°C

‌Insulation Voltage‌: 3800 V RMS, compliant with EN 50178 safety isolation standards

‌Mounting‌: Chassis mount with single-bore through design (φ30.2 mm), compatible with standard M6 mounting screws for seamless integration into distribution panels or control modules

‌Certifications‌: Complies with EN 50155 (railway applications), EN 50178 (industrial electrical equipment), and RoHS

LF505-S/SP25 ‌Applications‌
The LF505-S/SP25 serves as a core sensing element in critical industrial power systems, including:

Industrial variable frequency drives and servo systems for precise torque and speed control

Modular switch-mode power supplies (SMPS) and uninterruptible power supplies (UPS) to ensure stable output and accurate overload protection

DC fast-charging stations for electric vehicles, enabling real-time monitoring of high-current charging processes for enhanced safety and efficiency

Railway traction converters for energy recovery, braking control, and fault diagnostics

Photovoltaic and energy storage inverters to enable precise grid-current control and maximum power point tracking (MPPT) feedback

Welding power systems to ensure arc stability and consistent current waveform

‌Why Choose LF505-S/SP25 This Model‌
While not the latest generation, the LF505-S/SP25 remains a strategically vital component in industrial automation. It shares identical electrical performance, mechanical footprint, and certification compliance with the SP28 model—differing only in internal batch numbering. For systems requiring seamless replacement, long-term supply continuity, and zero engineering overhead, the SP25 delivers unmatched reliability. Its value lies not in innovation, but in ‌proven durability, consistent availability, and zero-failure operation‌ across tens of thousands of installations worldwide. Choosing the LF505-S/SP25 means selecting a sensor that has been validated by time, industry, and real-world performance—offering peace of mind where downtime is not an option.