“Resilience is not built in the moment the lights go out, but in the systems that restore them before anyone notices they were gone.” – MJ Martin
What is FLISR?
Fault Location, Isolation, and Service Restoration (FLISR) is an advanced distribution automation capability used in modern electric grids to automatically detect faults, isolate the affected section, and restore power to unaffected customers. It is often described as a foundational component of the “self-healing grid,” where the system responds to disturbances without requiring manual intervention.
At its core, FLISR integrates intelligent field devices such as reclosers, tie switches, sectionalizers, and sensors with communications networks and control systems such as SCADA or advanced distribution management systems. These systems continuously monitor voltage, current, and equipment status across the network. When an abnormal condition occurs, such as a short circuit or equipment failure, FLISR initiates an automated response designed to minimize the scope and duration of the outage.
Without FLISR, utilities rely heavily on customer calls, field crews, and manual switching operations to identify and resolve outages. This process can take hours and often results in larger outage areas than necessary. FLISR fundamentally changes this paradigm by compressing detection and response times into seconds.
How FLISR Works
FLISR operates through a coordinated sequence of detection, decision, and action. The process begins when a fault occurs on a feeder, triggering protective devices such as breakers or reclosers to trip and isolate the circuit. This initial protection step prevents equipment damage but creates an outage across a portion of the network.
The FLISR system then performs three key functions.
First, it locates the fault by analyzing data from sensors and fault indicators distributed along the feeder. These devices measure current flow, voltage loss, and fault signatures to pinpoint the faulted section with high precision.
Second, it isolates the faulted segment by opening switches on either side of the fault. This ensures that only the damaged portion of the network remains de-energized, preventing the outage from cascading further across the system.
Third, it restores service by automatically re-configuring the network. This is typically achieved by closing normally open tie switches to adjacent feeders, allowing electricity to flow from alternate sources and re-energize healthy sections of the grid.
More advanced implementations incorporate power flow analysis, feeder capacity checks, and distributed energy resource coordination to determine the optimal restoration path. These systems can operate in fully automatic mode or provide recommended switching actions for operator approval.
The entire process can occur in seconds to minutes, transforming what would traditionally be a prolonged outage into a short interruption for most customers.
Value to Electric Utilities
The value proposition of FLISR is both operational and financial, with measurable improvements in reliability, efficiency, and customer satisfaction.
When it comes to grid availability it is important to understand the definition of the network availability indicators and how they are reported.
The most relevant indicators for network availability assessment are:
SAIDI = system average interruption duration index
SAIFI = system average interruption frequency index
MAIFI = The Momentary Average Interruption Frequency Index
MAIFI is the average number of momentary interruptions that a customer would experience during a given period.
Each utility has its specific rules for accounting reliability indicators, some utilities may include major events or planned maintenance in the calculation, some others will not. Also, the quality and accuracy of reported data will impact the calculation of indicators.
From a reliability standpoint, FLISR significantly reduces outage duration and frequency, directly improving key performance metrics such as SAIDI, SAIFI, and Customer Minutes Interrupted (CMI). In some cases, studies have shown reductions in customer interruptions exceeding 50 percent per event.
Operationally, FLISR reduces the need for manual fault detection and switching. Utilities can dispatch crews more efficiently because the system narrows the fault location to a smaller search area. This leads to fewer truck rolls, lower fuel consumption, and improved workforce productivity.
Financially, improved reliability translates into stronger regulatory performance and reduced penalties. It also enhances service quality for commercial and industrial customers, where even short outages can result in significant economic losses. Faster restoration helps utilities retain and attract high-value customers.
Strategically, FLISR is a cornerstone of grid modernization. It enables better integration of distributed energy resources such as solar and battery storage, supports more dynamic network configurations, and provides a foundation for broader automation initiatives within the smart grid ecosystem.
Is FLISR Used in Canada?
Yes, FLISR is actively used in Canada and is becoming increasingly important as utilities modernize their distribution networks. Canadian utilities, particularly in Ontario, British Columbia, and Alberta, are deploying FLISR as part of broader Advanced Distribution Management System (ADMS) and smart grid initiatives.
Canadian vendors and software providers, including organizations such as Survalent, offer FLISR solutions tailored to municipal and mid-sized utilities. These systems are designed to address uniquely Canadian challenges, including long rural feeders, extreme weather conditions, and increasing penetration of distributed energy resources.
In Ontario, FLISR aligns closely with regulatory pressure to improve reliability metrics and customer outcomes. Many Local Distribution Companies (LDCs) are implementing FLISR incrementally, starting with high-impact feeders and expanding across their networks as communications infrastructure and automation capabilities mature.
Summary
FLISR represents a fundamental shift in how electric utilities manage outages. By automating fault detection, isolation, and restoration, it transforms the grid from a reactive system into a proactive, self-healing network. The result is a more resilient, efficient, and customer-focused electricity system.
In Canada, where utilities face geographic, climatic, and regulatory complexities, FLISR is not just a technological enhancement but a strategic necessity. As electrification accelerates and grid complexity increases, FLISR will continue to play a central role in enabling reliable and intelligent power delivery.
About the Author:
Michael Martin is the Vice President of Technology with Metercor Inc., a Smart Meter, IoT, and Smart City systems integrator based in Canada. He has more than 40 years of experience in systems design for applications that use broadband networks, optical fibre, wireless, and digital communications technologies. He is a business and technology consultant. He was a senior executive consultant for 15 years with IBM, where he worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin served on the Board of Directors for TeraGo Inc (TGO: TSX) and on the Board of Directors for Avante Logixx Inc. (XX: TSX.V). He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology. He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now Ontario Tech University] and on the Board of Advisers of five different Colleges in Ontario – Centennial College, Humber College, George Brown College, Durham College, Ryerson Polytechnic University [now Toronto Metropolitan University]. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees – in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and seven certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has completed over 80 next generation MOOC (Massive Open Online Courses) [aka Micro Learning] continuous education programs in a wide variety of topics, including: Economics, Python Programming, Internet of Things, Cloud, Artificial Intelligence and Cognitive systems, Blockchain, Agile, Big Data, Design Thinking, Security, Indigenous Canada awareness, and more.