Current differential relay

The ALP series covers differential protection and accounts for current transformer errors by providing a two slope differential setting characteristic. The events of transformer ultrasaturation during inrush and very low second harmonic content are properly covered by the unique SECURE blocking algorithm.

  • Application for up to six winding transformers
  • DNP3 and IEC61850 GOOSE communication
  • Cybersecure to help meet NERC CIP requirements

Hardware configurations

  • ALP-2000 : Combination of twelve (12) current and voltage inputs, six (6) digital inputs, four (4) relay outputs, two (2) high-speed power outputs, up to four (4) fiber Ethernet ports


  • ALP-4000: Combination of twenty-four (24) current and voltage inputs in a single device, sixteen (16) digital inputs, sixteen (16) relay outputs, eight (8) high-speed power outputs, up to four (4) fiber Ethernet ports

Main characteristics and advantages:

  • Includes ANSI functions 24, 27, 50, 50N, 51, 51N, 59, 67, 81, 81R, 87T and LOV
  • Platform built with the most cutting-edge technologies, resulting in very high processing and storage capacities
  • SECURE blocking adapted to ultrasaturation phenomenon of modern transformers
  • Fast transformer differential restrained action as low as 1,4 cycle to keep your transformer safe and avoid false tripping under magnetization current
  • Better precision of analog readings
  • One of the highest sampling rate in the industry, enabling precise recording and analysis of faults
  • Secure, rugged and reliable protection relay, in compliance with the latest utility standards
  • Protection, automation, metering and monitoring functions built into a single product
  • User-friendly interfaces and software for easy engineering, configuration, commissioning and operation
  • Scalable solution for the detection and treatment of non-conventional electrical phenomena
  • Up to six winding transformers
  • Secured WEB server for easy and safe access to the relay settings, real-time measurements and oscillography recordings.