LEM LA 55-P 50A Closed-Loop Hall Effect Current Transducer

The LEM LA 55-P is a precision closed-loop Hall-effect current transducer designed for electronic measurement of DC, AC and pulsed currents with galvanic separation between the primary power circuit and the secondary measurement circuit.

It has a 50A nominal RMS primary-current rating and a measurement range of 0 to ±70A. At the nominal 50A primary current, the standard LA 55-P provides a 50mA secondary current, corresponding to a 1:1000 turns ratio.

Product Specifications

Manufacturer	LEM
Model	LA 55-P
Series	LA55
Product Type	Current Transducer / Current Sensor
Sensing Technology	Closed-Loop Hall Effect
Measured Current	DC, AC and Pulsed Current
Nominal Primary Current	50A RMS
Measurement Range	0 to ±70A
Nominal Secondary Current	50mA
Turns Ratio	1:1000
Supply Voltage	±12V to ±15V DC
Accuracy at 25°C	±0.65% at ±15V supply
Linearity Error	<0.15%
Frequency Bandwidth	DC to 200kHz (-1dB)
Delay to 90%	<1µs
Operating Temperature	-40°C to +85°C
Primary Conductor Aperture	12.7 × 7mm
Mounting	PCB Mount
Approx. Weight	18g

Closed-Loop Hall Effect Measurement

The LA 55-P uses compensated closed-loop Hall-effect technology, providing high accuracy, excellent linearity and low temperature drift. The design enables measurement of bidirectional DC current as well as AC and pulsed current while maintaining galvanic isolation.

50A Nominal / ±70A Measurement Range

The standard LA 55-P is rated for 50A RMS nominal primary current with a measurement capability extending to ±70A, making it suitable for current feedback and monitoring in industrial power electronics.

Fast Dynamic Response

With bandwidth extending from DC to 200kHz and a specified delay of less than 1µs to 90% of the final output under the manufacturer's test conditions, the LA 55-P is suitable for dynamic current-control applications.

Typical Applications

• AC Variable-Speed Drives
• Servo Motor Drives
• DC Motor Converters
• Variable Frequency Drives (VFD)
• Uninterruptible Power Supplies (UPS)
• Switched-Mode Power Supplies (SMPS)
• Welding Power Supplies
• Battery-Powered Systems
• Industrial Current Feedback
• Power Conversion Equipment