Page 7 - Pipelines
P. 7
Electric railways
Electric railways produce
galvanically injected stray
currents which enter the
pipeline via the ground
through defects, thus
changing the potential of
the pipeline by means of
interference voltages.
corrosion
High-voltage lines
High-voltage lines generate
electromagnetic fields
which are injected into
parallel pipelines and
often occur in the form of electromagnetic
permanent interference fields
voltage.
U AC U AC
corrosion corrosion
Earth faults
An earth fault causes a
potential gradient area in
the surrounding soil whose
potential affects pipelines
located in this area. This
potential gradient area thus
spreads over to the relevant
pipeline network in the
form of an interference
voltage.
U
Lightning strike
Lightning overvoltage
generates transient
interference voltages
into nearby systems.
Injected via a potential
gradient area, they spread
over the entire pipeline
network.
U U
All these interference voltages may cause personal or material damage and a.c. corrosion. 7
