When a pipeline is located in the vicinity of a power line, it is subject to several electrical effects depending upon the operational status of the line. When a wire carries an electrical current, a magnetic field is produced around the wire which links the buried pipe. This linking causes an alternating voltage and current to be induced onto a parallel collocated pipeline. During an episodic upset from lightning or wires contacting each other during storms, a short circuit will occur know as a fault.
An unbalance will occur, which a factor ranging from several hundred to a thousand times with a corresponding increase in the induced voltage level. During a fault an additional coupling mechanism exists due to a portion of the fault current flowing into the ground at the faulted and adjacent towers. ACPT program uses the combined magnitude or total (kA) for the fault current calculations; not the X/R ratio. (X) in the power industry (I) or reactance over resistance (R).
The fault calculations in ACPT Fault application uses the combined magnitude of the total fault current (kA) and not the ratio. In other words when a fault occurs at a tower, ACPT it uses the total inductive current (either direction on the shield wires to the substations) and conductive current (ground).
This ground current flow adds an additional (conduction) component of voltage to that produced as a consequence of the magnetic field (induction). If the current is sufficiently large, a direct arc between the tower leg and the pipeline may be initiated which could lead to coating damage or pipe steel puncture.