802307 ELECTRICAL ENGINEERING FOR MECHANICAL ENGINEER Tarek M. Abdolkader
KINGDOM OF SAUDI ARABIA Ministry of Higher Education Umm Al-Qura University College of Engineering and Islamic Architecture Electrical Engineering Department 802307: ELECTRICAL ENGINEERING FOR MECHANICAL ENGINEER المملكة العربية السعودية وزارة التعليم العالي - جامعة أم القرى كلية الهندسة و العمارة الا سلامية قسم الهندسة الكهرباي ية Lecture 1 Description of the course Fundamental electrical quantities and laws
OUTLINE Description of the course Course outline Notices Grading policy Do we need Electrical Engineering? Fundamental electrical quantities and laws Charge Current Voltage Power and energy 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 3
Course Objective At the end of this course the student should be aware of the basics of electricity, DC circuit analysis and fundamental network theorems, AC circuit analysis, RLC circuits and transformer basics, and basic electronic devices. Brief list of topics to be covered: 1. Electricity and electric quantities 1 Week 2. Resistive networks 1 Week 3. DC circuit analysis theorems 4 Weeks 4. AC circuit analysis 4 Weeks 5. Electric Transformers 1 Week 6. Electronic Devices 2 Weeks 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 4
Resources Presentation slides: (not adequate alone) Lecture notes Textbook: John Bird, Electrical and Electronic principles and Technology, 2 nd Ed., Newnes, 2003. References: 1. Hughes, Electrical technology, 7th Ed., Addison Wesley, 1995. 2. A.E. Fitzgerald, Basic electrical engineering, McGraw Hill. 3. T. A.DeMassa, Electrical and Electronic Devices Circuits and Instruments, West Publishing Company, St. Paul, 1989. 4. P.J. Freeman, Electric power transmission and distribution, 2nd Ed., Harrap 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 5
1. Attendance of lectures is a must. Notices 2. Ask whenever you feel any ambiguity or confusion. 3. You have to read the text book along with lecture notes and presentation slides. 4. Solving a lot of examples and exercises is a must to get the skills needed to pass this course. ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة ادلين النصيحة 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 6
Grading Policy Semester works 40 Lab 20 Final exam 40 Attendence 5 Homeworks (HWs) 10 Quizzes 10 Midterm 15 Lab semester work 10 Final lab exam 10 Semester works 40% Lab 20% Final Exam 40% 0.5 grades are subtracted for each one hour absence in either lecture or Lab. Absence more than 25% of hours of the course (lecture and/or Lab) leads to Denial. HWs given in lecture are due before the next lecture. To take the grades of HW, you must come to office hours to discuss solution with the instructor. Two Quizzes are given with 5 grades each. The first Quiz is after the 4 rd week and the second Quiz is after the 10 th week Midterm exam should be after the 7 th week For each experiment, a report to be submitted After the 13 th week. No curve up 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 7
You need Electrical Engineering 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 8
You need Electrical Engineering 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 9
Charge 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 10
Current 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 11
Current A constant current (also known as a direct current or DC) is denoted by symbol I whereas a time-varying current (also known as alternating current or AC) is represented by the symbol i or i(t) 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 12
Average Current Where Q is the charge in Coulomb (C), I is the current in Ampere (A), and t is the time in second (s). Instantaneous Current i = dq dt 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 13
If a current of 5 A flows for 2 minutes, find the quantity of electricity transferred. See Problem 1 at p. 4 in the textbook Q = 600 C 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 14
The total charge passing through a conductor is given by: q = 5sin(4 t πt) mc Calculate the electric current at t = 0.5 s 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 15
Determine the total charge entering a terminal between t = 1 s and t = 2 s if the current passing the terminal is defined by: i = (3t 2 t ) A 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 16
Voltage 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 17
Voltage Mathematically, v ab = dw dq Where v is in volts (V), w is energy in joules (J), and q is charge in Coulombs (C) 1 volt = 1 joule/coulomb Like electric current, a constant voltage is called a DC voltage and it is represented by V, whereas a sinusoidal time-varying voltage is called a AC voltage and is represented by v. The electromotive force (e.m.f) provided by a source of energy such as a battery (DC voltage) or an electric generator (AC voltage) is measured in volts 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 18
Power and Energy 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 19
We write the relationship as: Power and Energy dw p = dt Where p is the power in Watts, w is the energy in joules (J), and time in seconds. From voltage and current equations, it follows that: p = dw dw dq dt = dq dt = vi p is the instantaneous power and is equal to the product of instantaneous voltage and current 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 20
Power and Energy It is important to realize that, just like voltage, power is a signed quantity, and that it is necessary to make a distinction between positive and negative power. The electrical engineering community uniformly adopts the passive sign convention, which simply states that the power dissipated by a load is a positive quantity (or, conversely, that the power generated by a source is a positive quantity). 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 21
Power and Energy Due to the conservation of energy, The algebraic sum of power in a circuit, at any instant of time, must be zero p = 0 In another form, The total power supplied = the total power absorbed The supplied by the source = VI The power absorbed by the resistor = VI 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 22
Power and Energy The energy absorbed or supplied between times t 1 and t 2 is: w t t 2 = 1 pdt When the power is constant we can use the simpler formula:: w= Pt = IVt Although the unit of energy is Joule (j), when dealing with large amount of electrical energy, we use the kilowatt hour (kwh). 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 23
A source of e.m.f of 5 V supplies a current 3 A for 10 minutes. How much energy is provided in this time? See Problem 7 at p. 6 in the textbook Energy = 9 kj 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 24
An electric heater consumes 1.8 MJ when connected to a 250 V supply for 30 minutes. Find the power rating of the heater and the current taken from the supply. See Problem 8 at p. 6 in the textbook Power = 1 kw Current = 4 A 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 25
An air conditioner of 3 kw power. How does it cost per month to operate this AC 10 hours per day. 1kwh costs 10 Halalah. 21/10/1432 Electrical Eng for Mech Engineer (802307) Lecture 1 Dr Tarek Abdolkader 26