Recent content by nazia_f

  1. N

    Java Solve Javascript Problem: 2 Dropdowns Menus

    Finally got it in correct shape. :biggrin: Thank you so much, Mark44 ! I can't tell you how much I appreciate your help. Thanks a lot! here's the code - <!DOCTYPE html> <html> <body> <script type="text/javascript"> function writeMonthOptions(){ var monthsName=new Array("Jan", "Feb"...
  2. N

    Java Solve Javascript Problem: 2 Dropdowns Menus

    Thanks a lot, Mark44. I tried to fix the problems you pointed out. I have tried to use GLOBAL variable this time and made 'daysNum' variable a GLOBAL one. But there's no result. I applied the similar sort of code for the 'month drop-down', then why isn't it working for 'day drop-down'? Is there...
  3. N

    Java Solve Javascript Problem: 2 Dropdowns Menus

    Hello! I am a newbie in javascript programming. I am trying to write a program where there will be 2 drop-down menu, one for month and another for days. There will be no content in the day 'select' tag at first but when a month will be selected from the month drop-down box, day drop-down will...
  4. N

    Why does Zener breakdown occure and why is it happeing?

    Thank you for helping me. I am going to study it a bit more.
  5. N

    Why does Zener breakdown occure and why is it happeing?

    I was reading Zener diode topic from Boylestad's book and there was a line that I didn't quite understand. It states - "Zener breakdown will contribute to the sharp change in the characteristics because there is a strong electric field in the region of the junction that can disrupt the bonding...
  6. N

    Why is maximum output power constant in field resistance control method?

    Ah I get it now. :) Thank you for trying to help me out. ^_^
  7. N

    Why is maximum output power constant in field resistance control method?

    Maximum torque is proportional to maximum armature current but armature current in inversely proportional to rotational speed. So we can write T = k/ω Again P = Tω = (k/ω)*ω = k So the power remains constant. This answer is what our teacher was expecting from us. Thanks a lot for your answer...
  8. N

    Why is maximum output power constant in field resistance control method?

    There are three speed control methods in a shunt DC motor - Field resistance control Terminal voltage control Armature resistance control In the field/flux control method induced torque decreases and speed increases due to decrease in flux, that is why power remains constant. This is what I got...
  9. N

    Transformer Voltage Regulation and efficiency determination?

    So given no-load current is the current that flows only through the primary when secondary is not loaded. Then it means - Imag = Ir-mag + Ix-mag = 0.15<-72.66° A is the Imag when secondary is loaded and though we have no-load current (0.15 A) given, we don't know its phase angle which means we...
  10. N

    Transformer Voltage Regulation and efficiency determination?

    Thank you very much for helping me solve the problem and also for keeping patience with me. If you don't mind I'd like to ask some things that confused me while solving the math. I didn't really get the concept of no-load current (In or Imag) = 0.15 A that was given in the problem. Is this...
  11. N

    What method is more accurate to find the turns ratio?

    I get it. Thanks a lot. I can explain it properly now.
  12. N

    Transformer Voltage Regulation and efficiency determination?

    Z2 = 1/{(1/57500<0°) + (1/15909.43<90°)} = 15332.7<74.54° Ω Z1 = 9.492<73.47° Ω V1' = {Z2/(Z1+Z2)}*Vp' = 2256.64<2.87° V V1'/V2' = N1/N2 so, V2' = (N2/N1)*V1' = 225.664<2.87° V Voltage regulation = {(225.664-230)/230}*100% = -1.89% How about now?
  13. N

    Transformer Voltage Regulation and efficiency determination?

    Ir-mag = (2278.8<1.39°)/(57500<0°) = 0.04<1.39° A Ix-mag = (2278.8<1.39°)/(15909.43<90°) = 0.14<-88.61° A Imag = Ir-mag + Ix-mag = 0.15<-72.66° A Ip' = I1+ Imag = 6.52<36.9° + 0.15<-72.66° = 6.47<35.6° A [Since the excitation branch comes after r1+jx1 is connected in series] Now, Vp' =...
  14. N

    What method is more accurate to find the turns ratio?

    I understood the fact that no-load voltage ratio is more accurate because almost all the impedance gets canceled due to very low current flow. I also got the fact that in loaded condition due to current flow significant amount of voltage drops across the impedance of primary and secondary side...
  15. N

    What method is more accurate to find the turns ratio?

    Which method of determining turns ratio is more accurate and why? 1. From the voltage readings in no-load condition 2. From the current reading in loaded condition We used an auto transformer (VARIAC) to supply voltage to a single phase transformer. Supplied voltage was 220 V. Then we...
Back
Top