Masters Theses


"Schweitzer Engineering laboratories (SEL) donated the SEL 387, SEL 311L, and SEL 351S relays and the SEL AMS to Missouri University of Science and Technology. This thesis documents the demonstration approach to set the SEL 387 relay to protect a grounded wye-grounded wye transformer and then test these settings by injecting fault currents into the relay using the SEL AMS. This thesis explains the approach to set the differential element of the SEL 387 relay to protect a transformer against internal faults and the overcurrent element of the SEL 387 relay to protect transformer against external faults. A radial power system model is assumed and modeled using ASPEN Oneliner and Power Flow software. Fault currents obtained from ASPEN model are injected to the relay using the SEL AMS. Separate tests are performed for the differential element and the overcurrent element. The objective of testing the differential element is to show that it is tripping for internal faults and restraining for external faults. The approach used by the SEL 387 differential relay to make trip decisions is theoretically calculated. These theoretical results are verified with results obtained from the relay fault event reports. The instantaneous and time overcurrent elements are tested by running various types of faults at four different locations. The objective of testing the overcurrent elements is to show that the instantaneous overcurrent elements are tripping only for transformer primary side faults and to show that primary side time overcurrent element is coordinating with the secondary side time overcurrent element"--Abstract, page iii.


Crow, Mariesa

Committee Member(s)

Shamsi, Pourya
Joo, Jhi-Young


Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering


Missouri University of Science and Technology

Publication Date

Fall 2016


xiv, 142 pages

Note about bibliography

Includes bibliographical references (pages 140-141).


© 2016 Aamani Lakkaraju

Document Type

Thesis - Open Access

File Type




Subject Headings

Electric transformers -- Testing
Protective relays
Electric relays
Electric power distribution

Thesis Number

T 11036

Electronic OCLC #