Overvoltage Protection

Course Description

Traveling waves, the wave equation, reflections and refractions of travel waves. Surge classification according to IEC 60071-1. Switching of unloaded lines and cables, transformers and reactors. Very steep surges in metal-enclosed switchgears. Surge arresters, the principle of operation and the protection zone. Selection of MO arrester parameters. Protection of overhead lines against lightning. Protection of switchgear, transformers and generators. Lightning protection system of the sensitive objects. Surge protection of low voltage (LV) systems and surge protective devices in LV systems. Surge and surge calculations in EMTP programs.

Learning Outcomes

  1. distinguish and classify surges
  2. relate the causes and consequences of overvoltages
  3. analyze the occurrence of overvoltage and the necessity of using surge protective devices
  4. associate terms that define surge protective devices
  5. calculate and analyze the occurrence of surges in simple simulation circuits
  6. apply EMTP programs in simulation of surge and surge protection

Forms of Teaching


Two school hours a week.


Two school hours in nine weeks.

Independent assignments

Solve the problem of overvoltage protection in EMTP.


Principle of operation of surge arresters. Current through surge arrester at Uc and Ur.

Week by Week Schedule

  1. Introduction to overvoltage protection
  2. Overvoltages in power system
  3. Analytical solving of overvoltages in electrical networks
  4. Laplace transform in overvoltage protection
  5. Oscillatory circuit - Parallel and series resonance
  6. Numerical solving of overvoltage in electrical networks
  7. Theory of traveling waves, Reflection and refraction of traveling waves - Bewley lattice diagram
  8. Midterm exam
  9. Petersen's rule
  10. The passage of travelling wave through the inductor, The passage of travelling wave nearby capacitor
  11. Analysis of travelling waves entering substation
  12. Travelling waves with steep front entering oscillatory circuit
  13. Overvoltage and overcurrent protection of the high voltage (HV) and low voltage (LV) systems
  14. Protection equipment of the HV and LV systems, operating principles and selection
  15. Final exam

Study Programmes

University graduate
Electrical Power Engineering (profile)
Specialization Course (3. semester)


Neville Watson, Jos Arrillaga, J. Arrillaga (2003.), Power Systems Electromagnetic Transients Simulation, IET
Peter Hasse, Institution of Electrical Engineers (2000.), Overvoltage Protection of Low-Voltage Systems, Revised Edition, IET
M. Padelin (1987.), Zaštita od groma,, Školska knjiga
Dehn + Söhne (Neumarkt i.d. OPf.) (2014.), Lightning Protection Guide,

Laboratory exercises

For students


ID 222708
  Winter semester
L3 English Level
L1 e-Learning
30 Lectures
18 Laboratory exercises

Grading System

85 Excellent
75 Very Good
60 Good
50 Acceptable