Course detail

Diagnostics and electrical equipments protections

FEKT-MDJZAcad. year: 2015/2016

Faults and protections against overcurrents in electrical equipments. Protective devices and their characteristics. Protection of cables and wires aganist overloads and short circuits. LV motors and generators protection. Protectin devices for transformers, capacitancies, batteries etc. Protection of semiconductors. Overvoltage protection devices. Protection against electric shock, residual current devices.

Learning outcomes of the course unit

Students can describe:
- principal of function of various protective devices
- principals of protection against overcurrents for individual kinds of devices
- principals of selectivity determination
- principals of protection against electric shock
- principals of overvoltage protection

Students can explain
- meaning of parameters of protective devices
- phonemena influencing design of protection for electric devices
- kinds of selectivity between protective devices
- principals of individual protective provisions for protective measure automatic disconnection of supply
- overvoltage origin and protection against it

Students are able to design
- cables protection against overload and short circuit
- protection of motors and inlets to them
- protection of transformers
- protection of semiconductors
- selectively connected protection devices in series
- electric circuit from the automatic disconnection of supply point of view
- individual levels of overvoltage protection

Students are able to analyse
- effects influencing protection of electric devices
- effetcts of short-circuit currents
- appropriate usage of protective devices

Students are able to judge
- correctness of overcurrent protection of electric devices
- selectivity between protective devices
- protection of surge arrestors
- fulfillment of conditions for protective measure automatic disconnection of supply

Students are able to compose
- report concerning protection of electric devices
- protocol on short circuit calculation
- protokol on measurement of important parameters of protective devices


The subject knowledge on the Bachelor´s degree level is requested. Requested knowledge: - to solve electrical circuits by the method of circuit simplification and nodes potentials - knowledge of electrodynamic forces effects and calculation - knowledge of thermal effects of electric currents in steady state and during transient period - calculation of short-circuit currents in LV networks - classification of electrical switching devices based on the ability to switch various currents - phonemena during motor start - function of a transformer - knowledge of regulation 50/1978 Sb.


Not applicable.

Recommended optional programme components

Not applicable.

Recommended or required reading

Tříska J.:Jištění,SNTL 1962 (CS)
Franken:Jištění elektromotorů,SNTL (překlad z něm. j.) (CS)
Havelka a kol.:Elektrické přístroje,SNTL 1985 (CS)
Bašta a kol.: Měření na elektrických strojích, SNTL 1959 (CS)

Planned learning activities and teaching methods

Teaching methods depend on the type of course unit as specified in the article 7 of BUT Rules for Studies and Examinations.
1. Lectures on each subjects (P1-P13).
2. Lectures are practised during numerical, computer and laboratory tasks every week.
3. All texts are available in faculty system.

Assesment methods and criteria linked to learning outcomes

exam - 100 points

Language of instruction


Work placements

Not applicable.

Course curriculum

1. Kinds and origin of faults in electric devices
2. Parameters and characteristics of fuses
3. Parameters and characteristics of circuit breakers and other protective devices
4. Wires protection against overload
5. Calculation of short-circuit currents
6. Wires protection against short-circuit currents
7. Motor and motor inlets protection
8. Transformer protection
9. Protection of semiconductors and other devices
10. Selectivity between protective devices
11. Protection against electric shock
12. Protection against overvoltage
13. Excursion


Students will understand characteristics of electrical protective devices and their usage for protection of individual types of electrical devices.

Specification of controlled education, way of implementation and compensation for absences

The content and forms of instruction in the evaluated course are specified by a regulation issued by the lecturer responsible for the course and updated for every academic year.

Classification of course in study plans

  • Programme EEKR-M Master's

    branch M-SVE , 2. year of study, winter semester, 6 credits, optional specialized

  • Programme EEKR-M1 Master's

    branch M1-SVE , 2. year of study, winter semester, 6 credits, optional specialized
    branch M1-EEN , 2. year of study, winter semester, 6 credits, optional interdisciplinary

  • Programme EEKR-CZV lifelong learning

    branch ET-CZV , 1. year of study, winter semester, 6 credits, optional specialized

Type of course unit



39 hours, optionally

Teacher / Lecturer

Computer exercise

4 hours, optionally

Teacher / Lecturer

Laboratory exercise

22 hours, optionally

Teacher / Lecturer


eLearning: opened course