Collection of  Electrical Questions and Answers:

Electrical Question and Answers Part-1

Electrical Question and Answers Part-2

Electrical Question and Answers Part-3

75 Responses to ElectRICAL. Q&A

  1. Pranav Jani says:

    Hi Jignesh,

    first of all, many many thanks to organise such a informative contents of electrical engineering. I appreciate this a lot. I have gone through many websites but didnt found so much useful information which I found on your website..brave effort.

    My electrical background is not so fundamental so would like to ask u a question regarding underground cabling of medium voltage cables for pv projects.

    I m looking for indian standards of medium voltage and low voltage cable specification for mega watt pv project.

    Will u pls guide me on this?

    Thank you.

    kind regards,

  2. G.R.Prasad says:

    What is the minimum clearence required around the neutral CT used for REF protection in 415V system.

  3. Senthilkumar says:

    please give details about SC rating design details for MDB and SMDB bus bars

  4. nalini says:

    nice question and answers sir,its very good…

  5. vishwa murthy says:

    Dear Jignesh ji,

    I want to know how to calculate the string efficiency, can you please send/post the details…it will be most helpful for me.

  6. Gnana Reuben says:

    Dear Jigneshji

    Thnaks a lot for the Current ratings, Gland Chart and Q&A Part 1 thru 3

  7. Madhurjya says:

    State whether a lamp rated for 230 V, 60 W can be used for both a.c & d.c supply. Give the reasons to your answers.

  8. selvanayagam.a says:

    hai sir.your Q/A everything useful.but how down load for pdf that about explain me

  9. Adil says:

    Thank u and please keep going

    Very good job

  10. Tshwarelo says:

    I enjoyed data that i got here.

  11. Jones says:

    Its really awesome,

  12. kuppuraj says:

    thank you sir…………………..!

  13. NEHA GETHE says:

    its 2 gud sir…..

  14. kandasamy says:

    very very useful site

  15. dear jignesh sir,
    i want to know that is there any chances of load on energy meter if indivisual neutral is not provide?

  16. how to calculate the current of a transformer?

  17. elias says:

    i like ur page thanks a lot cause i imrove my knowledge. thanks a lot.

  18. Pravin mali says:

    Nice site.thanks sir.

  19. Eneyo Duke says:

    Please is DOL applicable to lamp or only motor?

  20. Watch Dogs Ps3 says:

    I’m impressed, I must say. Seldom do I come across a blog that’s equally educative and amusing, and let me tell you, you have
    hit the nail on the head. The issue is something too few people are speaking intelligently about.

    I am very happy I found this in my search for something concerning this.

  21. m.balagurunathan says:

    Differences between providing the MCC with and without the relays.

  22. john says:

    2. A final circuit consists of six heaters connected in parallel each having a resistance of 150Ω. Find (i) the total resistance of the circuit (ii) the current through each resistor if the supply voltage is 600 V.

  23. parikshit gorai says:

    thanks for your valuable notes regarding cable trays.

  24. Francis lungu says:

    what is maximum mega ohms on 11kv 3core cable

  25. sureshbabu says:

    good evening sir, what is genarators check list and genaral maitanance

  26. Appeagyei says:

    Hi Engineer Jignesh,

    I know loss of neutral on a 3 phase system causes voltage on phase with less load to rise and that of the phase with high load to fall. please explain how and why this happens

    Thank you

    • The absence of Neutral will cause the total voltage to rise upto 380V between 2 phases. So as per voltage dividing rule it acts as a serious combination of two parallel branches if without earth or neutral in between. Hence the serial branch which has more LOADS ( means effective resistance low because parallel connection ) will hae less voltage across it. Remember current is same.

  27. Danish says:

    hi jignesh
    can you help me out regarding , what we have to see or note the important points when we are reading the specification for the electrical equipment eg ..transformer, ups , fire alarm ,cctv, acess control , hv switchgear , busbar ,mdb ,smdb, etc can you please help me out on this
    and keep going

  28. RamKumar says:

    sir, How to do Hi-pot test (DC)

  29. Vinoth Kumar says:

    Thank You very much for this collection sir.. It helped me in my career.

  30. weljoe says:

    What is the acceptance resistance of low voltage cables?

  31. vidya says:

    Its a very good explanation..very clean nd clear. .soo great..thaank uu sir.

  32. Akif Qadeer says:

    How to choose Accuracy class of CT?
    Lets say Meter is of 0.5S or 0.5 accuracy!!

  33. bramhanand says:

    sir i want to know about the dynamic impedance of ht motor at the time of start

  34. Saiju Joseph says:

    Dear Jignesh.Parmar,

    How i calculate capacitor bank breaker (ampere) capacity ?..example 80kvar capacitor if i connect in MDB,

  35. Vishnu G says:

    I wants to know about different ferrules and its meaninga

  36. P M Pavan Kumar says:

    Dear Sir,
    When we connect the capacitor bank to the motor, will it draw current continuously or not? Please reply.

  37. Hlonie says:

    What causes inductance in a circuit

  38. c.b singh says:

    hello sir
    i have a question that if i have a sub station with a transformer capacity 5MVA i have to erect 3 feeder of 18 to 20 Km each then how can i select size of conductor. these feeder are for rural areas

  39. Amrit Kumar Mohanta says:

    Hello Sir,
    My question is regarding on power flow analysis. I want to know that, what is the X/R ratio of Grid. It is require for simulating in ETAP

  40. Pankaj tiwari.k says:

    Why motor ratings are in h.p not in kw?

  41. tony says:

    hae,i acknowledge the good work on this website..l am an electrical engineering graduate at diploma level however the job market is flooded.i would like to pursue plc programming studies to add value to my carreer path…at what degree will it enhance my chances in the job market?

  42. MOHAMED HAROON says:

    who is best electrical conduit for lighting and socket

    A) Rigid Non Metallic Conduit (PVC)
    B)Rigid Metal Conduit (RMC) / Rigid Steel Conduit (RSC)
    C)Intermediate Metal Conduit (IMC)
    D) Galvanized Rigid Conduit (GRC)
    E)Electrical Metal Tubing (EMT)
    F) Flexible Metal Conduit (FMC)

  43. Bassey Friday says:

    How to calculate correct cable size for a 37kw ac motor and the correct gen for. A factory with 950kw load

  44. Tarun says:

    I have a project to design a food court in kundali. in this there are two nos. of coffee shop, one nos. KFC outlet & 12 nos of small FNB outlets of 600 sq.ft. area.
    I have to prepare a electrical load sheet.i’m confused how much load should i take, my senior suggest take 100kW for KFC and 40kW for coffee shop & 20kW for rest of the outlets.
    But it seems too much load we have taken.
    & how much diversity we would take?
    Please help sir what to do.

  45. Danish Hayat says:

    Dear Sir
    Could you plz help me out regarding the diversity factors to be considered for different panels . Do i have to consider diversity factor for all MDBs & finally diversity factor in main LT panel . Is there any code which says about diversity factors at different levels of distribution.

  46. Pradeep Khandagale says:

    Good morning ,
    Jiganesh sir,
    I want Indain standaras; & NEC Rules For E.H.V. Transmission line & EHV substation up to 400 kv.
    Thank you.

  47. saumya says:

    how can i calculate current carrying capacity of copper wire

  48. Hi sir, I am so happy to know your side…I want to know how a tube-light work.and it circuit diagram…estimation and cost.

  49. suresh says:

    Hi Sir,
    I have charged 132 KV S/C Line 35.9 Kms in length . There was no terminal equipment like LAs & CVT at receiving end . This line remained charged for more than a month and then whole assembly of R_phase got punctured further lead to snapping of conductor at T8 near to receiving end. Kindly let me know whether the above breakdown was due to Ferranti effect of the line or weak insulation of Disc insulators or high earthing resistance of line ?

  50. Ravi kant says:

    nice Q.

  51. tanzeel says:

    Hello everyone. Can any body tells me that RCBO C32 and R30 100mA, in this RCBO, what is meant by C in C32 and R in R30??

  52. prabhat says:

    very good info

  53. Shreyas says:

    caterpillar 1000kva .800 kW ..stops automatically in between what may be reason ?

  54. All electrical q&a sending for my mail ID

  55. Sameer Bhoi says:

    i never seen this type of website to learn about electrical.

  56. Sandeep says:

    Our vertical flange mount motor with centrifugal pump driven motor capacity 70 KW 3 ph Induction motor become vibration when motor run through VFD.

    Vibration occur only 1200 RPM to 1350 RPM DE-NDE V- 5.9 mm/s H- 7.9 mm/s A- 1.2mm/s. If motor run at full load then vibration is normal below 2.5 mm/s.

    What is actually problem. i am also take vibration at no-load also but same problem.

    I am also changed motor at foundation but same problem observed.

    Please give me technically ans….

    Sandeep Dalal

  57. Hothifah says:

    I am an electrical engineer and I am still fresh. I am studying the Steam turbine Generator and I have an STG connected to a grid (60 Hz,34.5 KV), the output STG power is 26 MW I need to increase it to 31.2 MW. I need to focus into generator side not prime mover. The question,

    1- What is the primary step I should do ?
    2- What graph should I study (Capability curve, v/f .. etc) ?
    3- How can I know what is the maximum Active power ?
    4- What is the logic and control that prevent the generator to feed more ?

    I appreciate your help..


  58. question says:

    question:estimate the material required for cts wiring system used in a hall measuring 30’*60’and height 10’and the reuirements are as follows: no.of lights points=32.no.of fan points=6.no.of 2pin plug sockets=2

  59. HARSHAD KOLI says:

    GREAT support

  60. Nikhil says:

    Thank q for providing such a website for electrical information

  61. Hardik Kotadiya says:

    Good question nd answer

  62. Dear sir,

    what will happen if we are not done earthing or disconnect earthing the switch gear (33kv switchboard indoor type)all CT & PT Star points are connected to same earth bus

  63. eihtwe says:

    Thanks a lot for your sharing.Your notes are very effective to me.

  64. Vijay Yadav says:

    . Due to this improve my basics

  65. Thanks Boss. Tapas Banerjee

  66. sri alex says:

    what is meant by safety factor in electrical??
    how can calculate the safety factor??
    plzz answer me fast..


  67. Faheem says:

    I have a chiller which is consuming 1.2 MW of power daily and voltage is 4.160V.How to calculate it in kWh?

  68. Hariprasad says:

    what will happen If u give a same body earthing for AC and DC equipment’s?

  69. Thangavelu Kumnar says:

    In which base REF protection act as earth fault protection explain please

  70. Thamizh says:

    Hello..sir. what is the procedure to remove moisture from HT panel.

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