EE205: Electric Circuits II (092)

Homework-assignments      Exams

Notes & Summary

Computer Assignments

Useful Links

Common Mistakes

Alsalam Alaikum wa Rahmat Allah

Dear EE205-Student,

Welcome to EE205. I pray Allah that you find this course very useful and enjoyable. An excellent start is needed.

This page serves my students in all semesters. It contains model exams, projects,...etc . Some material may be found through WebCT.

Best regards,

Dr. Ali Muqaibel

EE205 -092 Class

Pictures of inductor & capacitors (ppt)

Others

Course Syllabus-092_v1

Homework assignments  092

Exams

Exams 031

Notes & Summary

Projects

Useful Links:

• Electronic Workbench : Software Download

• Online lectures are available at the following link http://ocw.kfupm.edu.sa

Common Mistakes:

These are some common mistakes.... if you find additional common mistakes send them to me to list them. This way  we can avoid them and make them less common

1) Analysis of Balanced Three Phase Circuits

• Mixing angular frequency (rad/sec) with frequency in (Hz). Do not forget to do the proper transformation.

• Remember that adding or subtracting 360 degrees does not change the angle. (240 is equivalent to -120). Also when using the calculator do no forget to make sure that it is set properly to radians or degrees.

• When asked to find the three phase voltages or currents, do not forget to find the values for the other two phases.

• cos is used as a reference with angle zero. If sin  is used it has to be converted to sin if need be. sin x= cos (x-90).

• Line Voltages (V_AB,V_BC,V_CA or V_ab,V_bc,V_ca) does not equal to voltage drop across the line (V_aA, V_bB, V_cC). This is a very common mistake.

• If the frequency is negative do not forget to do the proper change on the angle.

• When using the equation for complex power, the conjugate is usually forgotten.

• If the total power is given do not forget to divide by 3 to draw the single phase.

• If the load is given as delta, you need to divide by three to draw the single phase equivalent.

• If the complex power is give as P+j Q, we cannot directly represent this as resistance and inductance !

2) Natural & Step response of Series and Parallel RLC Circuits

• alpha for series is different than alpha for parallel circuit. It is very common to mix them.

• When finding the type of response it is very common to compare mega^2 with alpha.. You should compare omega with alpha.

• After finding the constant in the response you should assign it to the proper exponent (or expression). It is very common to write A1 in place of A2 and so on.

3)

• For Q = 2π

Remember that the maximum energy stored is measured after summing W(t)_C & W(t)_L not individually and do not forget 2π.

• Q is measured at resonance.

• When finding the power lost in R do not forget 1/2 if I is an amplitude value.
• For impedance scaling :

            R'=k_mR            L'=k_mL             C'=C/k_m           ω_r'= ω_r             BW'= BW

• For frequency scaling :

                R'=R                L'=L/k_f             C'=C/k_f            ω_r'=k_f ω_r           BW'= k_f BW

• Do not mix up the symbols of poles "X" and zeros "O" in pole-zero plot.
• For the total energy stored in coupled coil

w(t)=1/2 L₁ i₁²(t) + 1/2 L₂ i₂²(t)  M i₁(t) i₂(t)

there is no 1/2 before M.

Here is a nice one