The Department of Energy Office of Electricity (DOE-OE) partners with INL on the Protective Relay Permissive Communication (PRPC) program to develop emerging solutions to protect the modern power grid from cyber and physical threats. One of the most important components of the electric power grid is the protective relay. When equipment fails or dangerous actions are initiated, relays protect power systems from damage. Protective relays provide protection against conditions on the power grid which could negatively affect the grid, damage equipment, or cause loss of life.

The PRPC program studies ways to transition protective relay equipment to a limited state. In a limited state, only the most essential relay functions operate. This constrained state represents an additional depth of defense of cybersecurity, while maintaining important business functions.

How PRPC Works?

The Protective Relay Permissive Communications (PRPC) program objective is to deliver a broad recommendation to industry on improving cybersecurity depth-of-defense for protective relays, and a simple technology device to support relay owners that has minimal impact to existing critical CIP requirements. The diagram below shows how the program works.

protective relay graphic how it works


Demonstrations and Workshops

Constrained Cyber Communication Device (C3D) Demonstration

Researchers at Idaho National Laboratory have developed and demonstrated a new technology to detect and block cyberattacks from impacting electric power grid operations. The technology, called the Constrained Communications Cyber Device (C3D), uses advanced communication capabilities to autonomously review and filter commands being sent to protective relay devices. If a malicious command is suspected, the device intelligently and automatically filters it out. Researchers collaborated closely with private industry, academia, and the U.S. Department of Energy’s Office of Electricity on its development as part of the Protective Relay Permissive Communication project.

Constrained COmmunications Cyber Device
INL’sC3D Demonstration Unit

cyberattacks, cybersecurity, cyber attack, ransomware, cyber security research, national and homeland security, homeland security
Researchers constructed a 36-foot long mobile substation and connected C3D to INL’s full-scale Power Grid Test Bed.

Western Area Power Administration (WAPA) Workshop

On February 23-24, 2022, INL’s PRPC team held a “Cybersecurity in Protective Relaying” Workshop at WAPA headquarters in Colorado. The Workshop included a Constrained Communications Cyber Device (CD3) demonstration and technical discussions about Master State-Awareness Estimator (MSE)

Workshop Purpose

  • Understand the need for cybersecurity in substations and specifically protective relaying.
  • Build awareness of electric utilities’ and industry’s efforts regarding cybersecurity in protective relaying.
  • Get suggestions and prioritization of industry needs for cybersecurity in protective relaying that may be developed in the next 2 years.

prpc workshop

prpc workshop WAPA


INL Media Contact

Ethan Huffman

Phone: 208-526-5015


INL PRPC Project Contact


Jake Gentle •