IEEE Electrification Magazine - September 2016 - 29

0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
4

9 10 11 12 13 14 15 16
Location (km)

Figure 8. A potential diagram of rail voltages. The b factor should be
between 0.3 and 0.7.

given to the overall effect on the running rails and other
structures that could be influenced.
Thus, before the polarized electric drainage is to be
installed, another measurement should be performed
according to the German AfK recommendation number
2 (Figure 9). The potential between the pipe and the rail
should be registered together with the potential
between the pipe and a reference electrode during for
example, a 24-h period. A correlation between both measurements must be calculated, and the coefficient of
determination (R2) must be found. This correlation can
be calculated with the aid of a simple spreadsheet program. By plotting one measurement as a function of the
other one, it is possible to adjust a linear function, and
the spreadsheet program can calculate and display the
coefficient of determination (R2) for this linear function.
The coefficient of determination must be bigger than 0.9
to indicate that the source of interference on the pipe is
indeed the rail line.

For Further Reading

Figure 9. Tools for a correlation measurement.

utilities will acquire corrosion on their pipes. The assessment tool to use in this case is a polarized electric drainage device, which is a diode with an anode that is
connected to the pipe, and the cathode is connected to
the negative busbar of the substation (the point of lowest voltage between the track and the earth). However,
the connection of any metallic structure to a return busbar in a substation, even via a polarized electric drainage
device, will increase the overall stray current. Therefore,
the connection of any metallic structure to the return
busbar should be made only with due consideration

U. Bette and M. Büchler, Taschenbuch für den Kathodischen Korrosionsschutz, 8th ed. Essen, Germany: Vulkan-Verlag, 2010.
F. Ollendorff, Erdströme, 2nd ed. Basel, Switzerland:
Birkhäuser, 1969.
USSR Ministry of Railways. "Instruction for the protection
of buildings, structures and metro systems from corrosion by
stray currents [Russian]."
C. L. Pires, Electrical Railway and Metro Engineering-From
Trolleybus to High-Speed Rail [Portuguese]. Rio de Janeiro, Brazil:
LTC, 2013.
Protection Against Corrosion by Stray Current From Direct Current Systems, BS EN 50162, 2004.
Railway Applications-Fixed Installations-Electrical Safety,
Earthing and the Return Circuit-Protective Provisions Against Electric Shock, IEC 62128, 2013.
Railway Applications-Track-Test Methods for Fastening Systems,
EN 13146, 2012.
Railway Applications-Track-Rail, EN 13674, 2011.
Reduction of the Corrosion Danger Due to Stray Currents in Tunnels of DC Traction Systems with Return Current via Running Rails-
Provisions and Bases for Calculations, VDV-Schrift 501/1, 1993.
Reduction of the Corrosion Danger Due to Stray Currents in Tunnels of DC Traction Systems with Return Current via Running Rails-
Measuring Methods, VDV-Schrift 501/2, 1993.
Richtlinie zum Schutz gegen Korrosion durch Streuströme von
Gleichstromanlagen, SGK C3, 2011.

Biography
Cassiano Lobo Pires (cassiano.pires@usp.br) received his
M.Sc., Ph.D., and Post-Doc. degrees in electrical engineering (EE) from the University of São Paulo, Brazil, after
completing his EE course. The subject of his research
was electric railway traction, including rolling stock and
fixed installations. Today he is with the Electrical Energy
Engineering and Automation Department of the University of São Paulo and is working at Alstom-System
and Infrastructure.
IEEE Elec trific ation Magazine / S EP T EM BE R 2 0 1 6

http://www.M.Sc

Table of Contents for the Digital Edition of IEEE Electrification Magazine - September 2016