Electrical Circuits and Electronics Reading (Tu 8:00) – Doc. Ing. Jan Chyský, CSc Lab. Exercises (Tu 16:00) – Ing. Josef Vlček, CSc Literature: Chapman Stephen J., Electric Machinery Fundamentals, McGraw-Hill Publishing Company, 1985, ISBN Crecraft D.I., Gorham D.A., Sparkes J.J., Electronics, Chapman&Hall 1993, ISBN Rizzoni Giorgio, Principles and Applications of electrical Engineering, McGraw- Hill Publishing Company ISBN Roadstrum William H., Wolaver Dan H., Electrical Engineering for All Engineers, John Wiley&Sons, Inc., ISBN

First Part Analysis of Electrical Circuits (Ohm’s law, Kirchhoff’s laws, loop and nodal analysis, principle of superposition. Thevenin’s and Norton theorems. Circuits supplied by DC and AC. Transient states in electrical circuits.

Second Part Electronics (Semiconductors, diodes, transistors, thyristors, operating amplifiers. Basic analogue and digital circuits)

Electricity at work National Grid Serves for distribution of electrical energy from powerplants to consumers

Distribution Systém

AC and DC electricity Voltage from batery is in one direction. Current flows from + lead to – lead Voltage on coils terminal when the coil is turned in magnetic field.

Single and 3 Phase Generator

Delta connection

Star connection One end of each phase coils is commonly linked to form a star or neutral point Voltage between any phase line and neutral is 1/sqrt(3) times that between any two phases phase/phase = 400 V phase/line = 230 V

Distribution

Circuit protection Means of isolating supply Means of protection against axcess current Means of protection against earth leakage

Circuit protection (2) Fuses and beakers must be accomodated to load. For motors should be used other fuses than for bulbs

Personal protection Preserve persons to injury by electric current. The injury causes current not voltage, but the voltage causes the current (Ohms law) I = V/R

System earthing Earth electrode Earthing conductor Protective conductor

System earthing ( 2)

System earthing (3) TN-S systém Uses separate protective PE and neutral N conductor

System earthing (4) TN-C-S systém Uses common protective PE and Neutral conductor

System earthing (5) Earth leakage protection

Safety of work Basic prescript - Law 50/1978 Sb Divides persons according their qualification §3 - Introduced workers §4 – Instructed workers (students in universities labotarory) Both paragraphs are valid for workers without electrotechnical educations

Safety of work (2) Terminology Living parts (hot) serves for current conducting, or aro under voltage or parts are conected vith voltage Non-living are construction parts regulary without any voltage or current. Due to concern some voltage or current may be there there

Safety of work (3) Incidence of electric curent on body

Safety current AC Hz DCcharge 1 mA3 mA 0,5  C parts which need NOT to be touch by personal during function 3,5 mA10 mA 5O  C Magnitude of current, when it is not possible to release hand. Current causes paralysis, suffocation >25 mA>100 mA----

AC HzDCCharge Limited constant current parts which have to be touch by personal during function 1 mA3 mA0,5 mC Parts which need NOT to be touch by personal during function 3,5 mA10 mA5O mC Magnitude of current, when it is not possible to release hand. Current causes paralysis, suffocation >25 mA>100 mA----

Contact voltage U d

Safety voltage AreaIn contact ( during handling ) Safety voltage of living (hot) parts [ V ] AC [V]DC [V] Normalliving50100 non living50120 Dangerousliving2560 non living50120 Extra dangerousliving1225 non living2560

Protection against dangerous voltage 1. Using isolation of living parts Basic isolation Suplementary isolation Double isolation 2. Using covering 3. Using barrier 4. Using position

Protection against dangerous voltage 5. Additional protection with current protector 6. Additional isolation (insulated pads, glove, etc.)

Protection using automatic disconnection in TN system Uses fuse or circuit breaker for disconnecting power supply