Fault Current Analysis Problems

TD A.5.1 - A basic electrical theorem states “the amount of current that will flow through a short circuit depends on two variable values: (1) __________ and (2) the connected total impedance of the current flow path from the source to the point of the fault.”

TD A.5.2 - Determine the Line-to-Line Fault in a system with a 100 kVA, 120/208V, 1ᶲ transformer (impedance Z = 1.21%), 150 ft 500 kcmil copper conductors (C = 22,185)

TD A.5.3 - Determine the Line-to-Neutral Fault in a system with a 100kVA, 120/208V, 1ᶲ transformer (impedance Z = 1.21%), 150 ft 500 kcmil copper conductors (C = 22,185)

TD A.5.4 - What thermal energy is created by a 12,000 amp short circuit in 0.01 seconds?

TD A.5.5 - The purpose of a Fault Current Analysis is to find the maximum available fault current at different points in the electrical system. This information can then be used to:

TD A.5.6 - A short circuit is typically, an unintended connection between two nodes of an electric circuit that bypasses the load and establishes a path of low resistance through which excessive current flows. Short circuits can occur between two phases, between a phase and neutral, or between a phase and ground. Short circuits can result in:

TD A.5.7 - Which of the following is not a source of short-circuit current:

TD A.5.8 - A building’s electrical service utilizes a 150 kVA, 480V, 3ᶲ transformer with an impedance (Z) of 1.2%. The closest over-current protection device is 125 ft. away. The conductors are 2 - #1/0 copper (“C” value = 8,925) in steel conduit. Determine the Line-to-Line Fault.

TD A.5.9 - Determine the Line-to-Line Fault in a system with a 150kVA, 120/240V, 1ᶲ transformer (impedance Z = 1.35%), 250 ft 500 kcmil copper conductors (C = 22,185)