Distribution Overcurrent Protection

Course Highlights | About the Instructor | Related Reports

Overcurrent protection of electric power distribution systems can be a complicated technical topic. Recent industry changes have added many more issues and components for the engineer to consider. This two-day course will provide a roadmap for engineers responsible for distribution overcurrent protection in the new environment. It assumes the engineer is generally familiar with symmetrical components and will use computer software tools to design the protection.

For that audience, the course focuses on an introduction to overcurrent protection, many examples, and new topics in the field. The goal is to provide the engineer with sufficient knowledge to conduct and understand computer-aided protection design studies. The course scope is limited to radial distribution systems up to 34.5 kV, either overhead or underground.


Course Highlights

  • Introduction

    • Purposes: safety, reliability, minimizing damage
    • Concepts: protective zones, selectivity, security, sensitivity
  • Protective device characteristics and ratings
    • Fuses
    • Circuit breakers
    • Relays
    • Reclosers
    • Sectionalizers
    • Current and voltage transformers
  • Distribution line protection
    • Setting considerations: time overcurrent, instantaneous, ground fault, fault impedance, cold-load pickup
    • Coordination scenarios: breaker-recloser, breaker-fuse, fuse-fuse, recloser-fuse, recloser-recloser, sectionalizers
    • Typical practices: reclosing, fuse saving, fuse blowing, adaptive settings, backup and breaker failure, automatic transfer, cable considerations
  • Substation transformer protection
    • Effect of grounding and winding connections
    • High-voltage fuses
    • Differential, directional, and feeder backup protection
  • Distribution transformer protection
    • Transformer loading constraints and failure hazards
    • Fuse selection and surge arrester coordination
  • Grounding
    • Three-wire and four-wire distribution; solid, low-impedance, high-impedance, and uni-grounded systems
    • Temporary overvoltages and ground fault sensitivity
  • Advanced topics
    • Using computer-aided tools: selecting a tool, study checklists, maintaining the models
    • Advanced relays: IEC 61850, DNP3, communications, fault recording and locating
    • Impact of overcurrent protection on reliability and power quality indices
    • Integrating high-penetration distributed resources on feeders
    • Arc flash hazards on utility distribution systems: models and evaluation techniques

This course incorporates material from two CEATI Distribution Asset Life Cycle Management (DALCM) projects: Report 5065 “Engineering Guide for Distribution Overcurrent Protection”, and Report 5079 “Arc Flash on a Utility System”. It also provides a chance for engineers to network and learn from others in this field.

About the Instructor - Dr. Thomas E. McDermott

Tom is President of MelTran, a power system consulting company based in Pittsburgh, PA. MelTran specializes in applied R&D for distribution systems and smart grid applications, distributed resource interconnection, custom software development, and electromagnetic transient studies. Tom has taught several short courses in distribution system engineering, and has co-authored nearly 50 technical papers, as well as one book chapter. He is Chair of the IEEE/PES Distribution System Analysis Subcommittee, Vice Chair of the Working Group on Distributed Resource Integration, and a task force leader in Cigré WG C4.502 on system performance impacts of long AC cables. Tom is a registered professional engineer in Pennsylvania. He has a B. S. and M. Eng. in Electric Power from Rensselaer Polytechnic Institute and a Ph.D. in Electrical Engineering from Virginia Tech.

More Information

For course bookings and more information about this course, please contact us.