Graduation Year


Document Type




Degree Name

MS in Electrical Engineering (M.S.E.E.)

Degree Granting Department

Electrical Engineering

Major Professor

Ralph Fehr, Ph.D.

Co-Major Professor

Wilfrido A. Moreno, Ph.D.

Committee Member

Lee Stefanakos, Ph.D.


3 phase fault, Breaker Failure, Extreme event, Gang Operated breaker, Independent Pole Operated breaker, Instability


The Bulk Electric System (BES) in the United States includes transmission lines of 100kV and above, transformers of 100kV and above on Low Voltage (LV) side and generating units that step up to 100 kV and above. The BES is a power network that connects different states and utility companies via tie lines for exchange of Power.

To maintain the integrity of power systems, it is very important to keep the BES intact and for that the regulatory authority, North American Electric Reliability Corporation (NERC), has developed over 100s of reliability standards and is responsible to enforce them.

During the past several years, the U.S has experienced power system instability events in which a fault occurred on one part of a system and travelled through the entire interconnection. Some of the extreme events are a major concern for power systems in the U.S that consists of Cascading, Uncontrolled Separation and natural disasters damaging the transmission circuits.

Protection System plays important role towards the stability of power systems, but most important aspect of protection system is the Critical Fault Clearing Time. This case study focused on the Critical Fault Clearing Time enhancement by making a comparison between a Gang Operated (GO) and Independent Pole Operated (IPO) Breaker. An extreme event was considered as a fault scenario for the case study that consisted of three phase fault followed by breaker failure scenario.

PSS®E 33.9 software was used to perform dynamic study on three different power plants to show the comparison between GO breaker and IPO breaker. A tremendous improvement was achieved using IPO breaker with more than 100% increase in Critical Fault Clearing Time.