Lec 05 Important Question Discussion on Symmetrical Fault Part I

Subject : Power System (Crash Course)
Faculty : Mr. Sohail Ansari Sir
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[@IrfanMujawar]

Lecture uploaded everyday at sharp 5 pm Hats off to your punctuality and sincerity.

[@TechPointClasses]

Exactly... Love the team and their regularity..

[@ladhavaravindr8862]

Xeq=(0.2×0.1/0.2+0.1)+0.15=j0.216 (note: take bus 2 and reactance X as series and bus 1 parallel than bus 3 C as series ) If(pu)=1/j0.216=4.615 scmva(pu)=1×4.615=4.615 scmva=4.615×100=461.5mva

[@runpacevictorymathematics]

Thank you sir You are great teacher I was afraid of this subject but now it seems that I can handle this too

[@shahinoorislam3161]

First of all thank you all the members Genigue Education team for giving us hopes. I'm loving your lectures Sohail Sir!!! Sir, In the first question we can also find reactance of the reactive by your MVA method. :) Since the restricted fault MVA is given which is 1500MVA. Let the reactance of the reactor be X in PU value. Base MVA= 100MVA Therefore. SC MVA of the reactor will be = 100/x Now, 1500= 1000+(2500||(100/x)) =>500= (2500×(100/x))/(2500+100/x) => 5/(1+25x) =1 => X = 0.16 pu Sir, Is it wrong to do in this way? And for finding rating of the CB. SC MVA at bus1 is 1500MVA( Fault level given in the question) and this will be the net MVA of circuit above the Circuit Breaker C (Since during fault condition all the current from generator1 and generator2 will flow through the fault point, therefore whatever fault MVA we get that will be the net MVA of circuit above CB C)and it will be in series with (100/0.15)( means parallel as like capacitor) = 461.53MVA Sir, Is it wrong concept? @Sohail Sir. Please reply Sir!

[@kakarotkaushal1793]

MVA method is the next love. Thank you sir!!!

[@upsccseaspirants6718]

Superb sir... Kya method batai hai aapne.... Thank you so much sir...

[@zaidmohammad7927]

Can anyone explain why the load reactance was considered shorted for generator A in second part of the question when fault MVA on bus bar was asked? For generator A the load should not be shorted. The load is not considered because we have assumed the load currents to be zero.

[@adityashrivastava8943]

i guess its a mistake

[@cookwithpanda6199]

In first question if load is motoring load, then it also contribute something to fault current.

[@manishthapliyal5886]

Sir IN MVA method, we took 1000MVA and 625 MVA in series , but taking 1000MVA and 2500MVA in series and their resultant in parallel with 625 MVA also seems correct. I am facing this problem because finding equivalent across a fault point always gives 2 possibility unlike equivalent impedances where terminals (2 nodes) were there.

[@rizwanalikhan9213]

MVA mehod is too easy..... awesome 👍👍👍😊

[@nayankarmakarofficial6294]

thank you so much sir... jst osm method....for yourself now I'm able to do many problem solve

[@krunalpatel3824]

Excellent coaching.... Thanks to Genique Team & Special Thanks to Sohail Sir.

[@surajrawat9645]

thanks a lot, by heart you are genius SIR sorry to say, after completing this course please go for machine, sir are god for us, who are doing self preparation, THANKS

[@Rajesh-yk9vw]

Be careful at 10.53 . current will flow through load because fault at B not short ckt the load.(simple network theory).There is a reactance between fault pont and load .

[@dhananjaykumar5114]

Very Good Lecture

[@SaritaSingh-xj3gu]

Sir question 2 Ko thevenin se nhi kr skte ...5=(1/.4j)+[1/(.3j+xj)]?

[@apurvsingh4047]

it's possible.

[@mayankojha2333]

Yes sir, i got answer from both remaining methods except mva method of SCMVA = 461 MVA.... Thank you sirji

[@milindbhandari2134]

Can you please post your solution of part 3 by first calculating fault current method

[@dr.strange2855]

In first question first I thought that you have to calculate reactor X conventionally i.e. it can not be calculated by mva method. Now, I have solved the complete question with only mva method😀😀😀😀

[@mritunjays4610]

masaallah greatness of MVA method

[@vikaschouhan310]

sirji jo concept 2 year me nh sik paya vo ek min me sik gya aapse

[@yuthivendra4179]

thank u sir for teaching MVA method

[@akratypatkar7962]

sir, why in reatance diagram ( solving part a of ques1) generator voltage is not considered ?

[@chiranjeevig8740]

thanks sir,the way you analysing questions is awesome

[@soujanyad3314]

Thank you sir for ur time and effort😍😍

[@bikramjithazorika2246]

Best concepts..

[@praveshyadav7436]

sir , ur way of teaching is just fantabulous

[@GeniqueEducationTeam]

most welcome..share this platform with others too..so that genique grow at faster rate..all the best.

[@praveshyadav7436]

@@GeniqueEducationTeam definitely !!!

[@bhaskarrao5254]

The mva method proved to be a flash type converter for scmva problems......

[@humanchakras]

Sir ,In First Question...if fault occur at one bus then whole current will pass through that bus...not from LOAD...even other generating bus is active.....Ye baat smjh nhi aayi..?... Then...where is the advantage of connecting more than 1 generator?...so that power supply will not cut...

[@santoshsaini8608]

First understand why we are doing fault current calculation. It is done to calculate the rating of protection devices. This fault current we calculated is set value for relays. If fault current is more than set value relay operates. So AFTER THE RELAY OPERATES FAULTY LINE WILL BE DISCONNECTED AND LOAD WILL CONTINUE TO GET THE POWER FROM HEALTHY BUS. BUT ALL THIS WILL HAPPEN AFTER THE RELAY OPERATES WHICH IS STEADY STATE OF SYSTEM. but fault current calculation we are doing in subtransient period (relay is not operated yet) , coz fault current is max in this time.(considering the worst case scenario). In this worst case scenario analysis is must 4 rating of protection devices.

[@humanchakras]

@@santoshsaini8608 thankyou so much Sir.

[@shreyashingale6247]

Sir @ 12:15 Xeq is j0.03467 not j0.3467

[@sumitkartik77]

Thanks sir for these videos, really helpful

[@sandhyakumari5063]

Sir sach me no one can beat you..

[@subhamsingh8610]

you haven't to prove yourself , you are genius.🤟

[@vijayprajapati1040]

yes...same thoughts

[@kushalroy2500]

Sir the MVA method is really awsome but please sir tell that why we take like capacitors when it is connected in series.

[@vaibhavdeepshah2810]

Awesome 👌

[@shwethak6895]

Sir, in 1)Q to find MVA rating of CB , by using MVA method we can find SCMVA equivalent in pu value right then to get MVA in actual value we need to multiple with MVA base right ? I am confused here, but u have taken that equivalent Pu value as MVA ??

[@ayushgupta6583]

Sir agar 1st question me....at circuit breaker C pucha hai...to fault ki location load se pehle kyu nhi li?? Uske baad me kyu li hai?? Please help sir...

[@ayushgupta6583]

Sir please help....

[@akmyt3035]

Sir MVA method is the best method and very easy

[@rohitseth6615]

Infinite likes for MVA Method...

[@TechPointClasses]

Sir MVA method maza aageya...😘😘

[@GeniqueEducationTeam]

share this method with others also..all the best.

[@surendrakverma555]

Thanks Sir 🙏🙏🙏🙏🙏🙏🙏🙏🙏

[@knowledge_follower]

Sir we can also calculate Sc MVA by 1/Xeq (PU), we do not need to calculate Fault current and then we will convert it into actual MVA. Is this right sir?

[@aloksahu7208]

Sir I am doing AMIE it is very much useful for me

[@bismazaffarele0278]

In question one we r considering fault level as MVA rating,,but in second question we r considering fault level as fault current ,,..how both can be one ???

[@sandhyakumari5063]

Sir ab sub ho jaye ga hum se...bahut der se wait kr rahe the sir is leacture ka ...thanku sir

[@GeniqueEducationTeam]

stick to the plan..u wont get any prblm..all the best

[@bismazaffarele0278]

@@GeniqueEducationTeam In question one we r considering fault level as MVA rating,,but in second question we r considering fault level as fault current ,,..how both can be one ???

[@gulamhussain8545]

Excellent lecture

[@sonubishwas5300]

Brilliant sir.... Maja aa gya

[@shriyamsingh5446]

sir ,1/(j0.3467) is not equal to 28.84.Your Xeq is wrong.But not an issue.Your method is very good.

[@developersclub3810]

Sir answer 12:13 is 0.03467 not 0.3467, just a minor correction in awesome video..!!

[@AbhishekKumar-ln7kq]

Sir aap bole the ki load also provides fault current in previous lacture but isme load current zero hai

[@competitioncurrentaffairsw2128]

Sir in Q1. In finding SCMA at bus 2 If(pu)=2.884 not 28.84 so by MVA method 2884 is different .

[@competitioncurrentaffairsw2128]

sir kindly answer the query please

[@HitanshuSaxena]

I read ur comment in query video. I just want to clear u that If= 28.84pu is correct. Sohail sir wrote Xeq = j0.3467. actually it came j0.03467. i hope this helps

[@gauravvyas2292]

In the very first question why are we taking Ef = 1. It's is mentioned that the system is on no load ?

[@nadeemshaikh9897]

Positive sequence diagram explain kijiye sir

[@swarajdey9035]

Sir gate 2020 bala qusn m aap xeq ase kse nikale... Xeq first case me to direct 0.4 ni hga kya kyuki fault current to short circuit bala path se flow hojayga to right side bala reactance se to current flow hogai nai to uska kya use

[@muralikrishna9563]

Sir tell me why in Gate 2000 question the calculated X equivalent is placed in series (calculated using given 3-phase fault current) while calculating system reactance. Why don't we consider C. B reactance in calculations

[@ravindranaththakur4174]

Sir you are great.

[@siddharthcchoudhari224]

Thanks sir Very excellent

[@s.t.saranya8407]

thank you so much sir

[@tagore147]

At 27:53 why did we assume emf of system(in pu)=1?

[@GeniqueEducationTeam]

If nothing is given the take 1 pu as base voltage/ base voltage equal to 1 pu only

[@srikanthsrikanth3540]

Sir in second question we taken E=1 pu...at bus 1...again we taken 1pu voltage at bus 3..... I.e where fault analysis can do at that point we can assume E=1p.u?

[@IrfanMujawar]

Voltages at various buses are assumed to be constant after fault that's why voltage during fault finding is taken as 1 p. u. unless otherwise mentioned.

[@poojayadav-wd3kr]

Sir for 1st question why aren't we taking that load terminal under consideration during fault

[@ankitshresth2117]

During a short circuit condition..current will travel the sc path rather to prefer in impedance path..

[@poojayadav-wd3kr]

@@ankitshresth2117 okay

[@ankitshresth2117]

How is ur preparation going..if u are preparing for ese,,can u suggest best video lectures for ict,material science??

[@poojayadav-wd3kr]

@@ankitshresth2117 sry right now I m preparing for gate

[@ankitshresth2117]

@@poojayadav-wd3kr I have almost completed my preparation,,thats why i am thinking to switch ese..only 8 non tech books has to cover..by the way,,best of luck!!

[@Sh-hx6uh]

Awesome sir

[@sruthykrishna6791]

Sir...In MVA method, inorderto find the value of X in pu.... we hv to consider it in the 100 MVA base... ryt?

[@skizajul4041]

Super mva concept

[@hemasundar8111]

If fault occur at bus 3 then x value of circuit breaker will remains constant why

[@jivi210692]

Superb 👌

[@kanthakborkar710]

👍

[@PradeepKumar-mm8pz]

Thank You Sir

[@gurudevsharma9786]

thank you nd sir mene last wale question ko slove kia mva method just assuming 100 mva and later i convert in pu and Epu taken 1 and got the same answer. is this correct??? bt overall this is the best method and time saving method question solve without making reactance digram thank sir

[@vinaydrm9953]

Agar load syn motor hua tab If change ho jaega...kya questions ban sakata hai iss k upar

[@bhabanimishra2984]

🙏

[@divakar8932]

superb

[@vikrantkale2474]

Muze toh dono method easy lage☺️

[@aryannishad316]

gjb sir...

[@musicrazera359]

1st question m when fault occurs at bus 2, then the current leaving from 1st generator have two paths to flow; 1 accross the load and the other accross the reactor X and then through the fault current path. It means this current should flow in both paths. So load can't be short circuited. I couldn't understand. Please explain someone. I understood 1st part when fault occurs at bus-1 but couldn't understand 2nd case when fault occurs at bus-2.

[@vinayakpb6012]

Fault at bus 2 means there's short-circuit at bus2 which means there's less resistance therefore current will take that path to flow.

[@Rajesh-yk9vw]

#musicrazer ..you are right . current will flow in load path when fault occurs at bus 2.(simple network theory).so u take the load reactance while calculating fault current at bus 2 .

[@real-talent5610]

Tq sir

[@creativesquare1110]

In the first question how one can assume the Bus 1 voltage to be 1 p.u.? As it's not mentioned in the question.

[@GeniqueEducationTeam]

if it not given then u can assume..otherwise other voltage value will be given in the question.

[@Kitti8892]

Bus 1 2 PR fault MVA nikalte wqt 3rd bus ki need q n h sir....

[@spidermama5597]

Sir aap machines kab shuru karenge??

[@mohnishkumarsahu1955]

MVA method is best

[@hemalathadevi9266]

please upload the videos in english sir

[@sujitmurmu1078]

Calculation smj m ni a ri h sir

[@004abhaysharma7]

sir 2.884 ara h calci me to

[@indrayogasana]

MVA method ❤❤❤

[@vinaybalwan3662]

Air is question me bus 2 per 1 p.u ku le rhe h, 2 p.u ku nhi

[@ladhavaravindr8862]

i can not find answer with fault current mathod of questions 3 answer about 3551 mva i take Epu =1pu it ok or not kind someone help me

[@ladhavaravindr8862]

ok i got mistake is that bus 2 and X reactance take as series and bus one in parallel than all take as series of bus C

[@JAIHIND-tj1cr]

1999 me jo double feeder wala question aaya tha usko mva method se please koi bta do.......

[@raahtherideofyoursuccess4161]

Sir x ka value 0.08 pu aa rha hai ..?1st qstn me

[@pritikakumari4859]

Fault level means fault current or scmva???

[@zaidmohammad7927]

SCMVA

[@dhanurbanpanim]

100/ Xeq p.u. = 1500 , क्या ऐसा कहना सही होगा ?

[@sandhyakumari5063]

Sir mvA method se solve kr sakete h aisa socha ni tha...itna aasani se ans aa jaye ga

[@nirdeshsingh8388]

Sir pu value greater than 1kaise hui???

[@Abhishekkumar-gs4zj]

The per unit value of a quantity is defined as the ratio of actual value to the base value of the same quantity (Both should be in the same unit). Now come to your question PU value can also be greater than 1 because it depends on the base value that may be less than the actual one.

[@zulfiquarali6205]

Normal method se 420 MVA aa raha hai mera

[@sasmitapraharaj4565]

Sir why Ef is1pu inall case

[@pritikakumari4859]

It is given in question... See the full question in previous year...

[@SebaAbhilasha]

Sir thanks for educating us, my doubt is why you took the reactance of generator 2 as 4%, because nothing is mentioned for the voltage at generator 2 or generator 1, how are we calculating the Xpu, is it because we are considering all of them are having same voltage rating?? Please advise.

[@rishikeshbhardwaj3845]

Yes we take the voltage rating same for all the components..

[@eletricalpopup8938]

Sir please teach in English