Short Circuit Analysis for Amacalan Distribution Circuit of TARELCO 1: Basis for an Intervention Program

Tarlac State University
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This study was conducted to determine the causes of interruptions and to
compute the magnitude of short circuit current at various locations of the
Amacalan Distribution Circuit of Tarlac Electric Cooperative 1 (TARELCO 1) to
evaluate the proper ratings of connected protective devices. By using short circuit
analysis programs written in MATLAB, the determination of the short circuit
current in terms of the following faults: Three-phase (3P), Single-Line-to-Ground
(SLG), Line-to-Line (LL), and Double-Line-to-Ground (DLG) were easily
implemented. There were nine (9) causes of interruptions encountered by the
Amacalan Distribution Circuit for the last five years; 87.78% can be attributed
due to short circuits. Of the four types of fault, DLG registered the highest
magnitude in nodes 1 and 2 while 3P dominated the highest magnitude of short
circuit current in the remaining nodes from nodes 3 to 19. The lowest magnitude
of short circuit current computed was LL in nodes 1 to 3, while DLG was lowest
in nodes 4 to 19. The existing main protective device were found to be sufficiently
rated and can safely protect the main substation in event of any short circuit while
other protective devices on the distribution circuit need to be replaced. It is
recommended to conduct a protection coordination on the Amacalan
Distribution Circuit that will include breaker-recloser, recloser-fuse, and fuse-fuse
coordination to immediately protect the system from destructive effects of short
circuit currents.

Keywords: Double-Line-to-Ground fault, Line-to-line fault, Short Circuit,
Single-Line-to-Ground fault, Three-phase fault