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Private tutoring??


robinson

Question

hey, this is my first thread so excuse me lol i have failed my level 2 unit 3 exam twice :( even with lots of revison and revision class's. I have spoke to my tutors and they seem no help, i have heard from tutors that if i fail it again then i automatically have to leave the course. i have an apprenticeship and really enjoy it so this exam is a major issue...still. i was wondering if anyone knew of any private tutoring around northampton or just general tips.

thanks

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hey everyone i know you all said you will help me with my questions but aint sure if i have to start a new post for it?? i will write it here and if no reply ill make a post :)

the question is..

The rotor speed in rev/sec of a six pole induction motor operating on a 50hz supply with a 4% slip will be:

i know that the formulae is...

NS = f

- therefore f= frequency and the p = pairs of poles.

p

so... 50

- = 16.6 but i cannot remeber what to do now like with the 4% slip???? i think its something easy like take away the 4% of 16.6 from it?? can anyone help???

and would the answer from that be rps or rpm?? if its rpm i just need to divide it by 60 but cant find the notes on what happens to the answer??

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hey everyone i know you all said you will help me with my questions but aint sure if i have to start a new post for it?? i will write it here and if no reply ill make a post :)

the question is..

The rotor speed in rev/sec of a six pole induction motor operating on a 50hz supply with a 4% slip will be:

i know that the formulae is...

NS = f

- therefore f= frequency and the p = pairs of poles.

p

so... 50

- = 16.6 but i cannot remeber what to do now like with the 4% slip???? i think its something easy like take away the 4% of 16.6 from it?? can anyone help???

and would the answer from that be rps or rpm?? if its rpm i just need to divide it by 60 but cant find the notes on what happens to the answer??

the answer would be RPMRPS.

16.6 x 60 = 999.9 RPM.

allowing for 4% slip, 4% of 1000 is 40, so it would be 960 RPM 4% of 16.6 is 15.99

EDIT: worked out RPM instead of RPS

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i know mate lol thats what i been using done so much revison and yeah i know but my tutors tell me that if i fail i cant go back whatever??? well confused! o well got the day off 2 revise even more i best pass i wasted a whole holiday in turkey for this lol well it werent wasted cause i know more lol

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hey thank you for your help i have had a look and the question has four muliple choice answers with it....

a.) 11.034

b.) 16.907

c.) 16.032

d.) 17.431

so do u have to do something with the part u just shown me ?? what you said is kind of what i thought but that dont match up to the answers given? thanks again

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hey i wrote a answer to you all in the quick reply and it dont seem to have come up have i done it right??? please let me know if not i will write a reply again

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hey thanks for all the replys to answer some of your questions... i am 18 and yeah i am on day release the exam is half health and safety which i find easy and the second is motors, ac theory and things like that, night class's are an option but i have gone to the ones for me at college and found they dont exsist or the tutor never turns up, the exam is realli soon. In the class i understand the work, i think i struggle with the wording of certain questions or just generally forget, it never seems to sink in.

here is a link for a website that i have been using but i think i only learn the questions that are on here therefore i wont know anyothers that come up in the exam.

http://www.swindon-massive.co.uk/electrical/revision/2360pt1/assessment_choices.html

please scroll down to unit 203 (just over half way down the page )Outcome 2,3,4, and 5 These are the areas that i struggle with. Thanks for all your replys again

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sorry, the question does say rev/sec, not RPM

50 / 3 = 16.6

16.6 x .96 = 15.99. close to C, but id have expected an exact answer? or has anyone else got a different answer?

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Robbo , if this is a quallie that you need to attain I can only suggest you do some mugging up, trouble is ,at 18 there are many distractions. Set some time aside for revision if you can , these days you really need to get these qualies under your belt.

I have no idea what courses you should be doing, I assume this is one of them . They have been changed over the years , all I remember are C&G ,s Elect. Installation A , B, and C . These were related to the grade system A = Electrician , B Approved Elect. and C = Technician.

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Andy

The way I was taught many years ago, then rotor speed would be 960RPM or if you like 16RPS.

The formula then was:

Speed (RPM) = 60 x f/pairs of poles, which is equals to

Speed (RPM = 60 x 50/3

Speed (RPM) = 1000 (this 1000 is the synchronous speed of the rotating magneting field)

Slip is the speed the rotor lags behind (and must) the rotating field. 4% =40RPM. Hence 960RPM.

Just in case it is of interest, the value 60 is what converts the frequency from 50 cycles per second to cycles per minute, which in turn calculates speed in revs per minute.

It seems the modern way to calculate RPM is to use the value 120 x f / number of poles ie 120 x 50/6 = 1000 same answer.

The 120 is called a constant.

Hope this is of interest.

Steve

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yeah i know i need to cheers mate :) i do revise alot and will continue are you a tutor or anything?? was wondering if you knew of any websites which are useful ??

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cheers thats better i think where did u get the .96 from ??

if you need a % off something, its always 1 - (number / 100). so if you need to take off 20%, time value by 0.8, if you need to remove 4%, times value by 0.96. just a shorter way

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Andy

The way I was taught many years ago, then rotor speed would be 960RPM or if you like 16RPS.

The formula then was:

Speed (RPM) = 60 x f/pairs of poles, which is equals to

Speed (RPM = 60 x 50/3

Speed (RPM) = 1000 (this 1000 is the synchronous speed of the rotating magneting field)

Slip is the speed the rotor lags behind (and must) the rotating field. 4% =40RPM. Hence 960RPM.

Just in case it is of interest, the value 60 is what converts the frequency from 50 cycles per second to cycles per minute, which in turn calculates speed in revs per minute.

It seems the modern way to calculate RPM is to use the value 120 x f / number of poles ie 120 x 50/6 = 1000 same answer.

The 120 is called a constant.

Hope this is of interest.

Steve

it still gets the correct answer, so just go with what you find easier

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When it comes to the exams the way I do it is,

-Go through the questions answer the ones that you know for sure and leave the ones your not to sure on.

-Then go back over the questions you were not to sure on and spend a bit more time thinking over the question, leave the questions you haven't got a clue about.

-That should leave you with the questions you just don't know, with these try and disregard the answers 1 by 1, that will give you a 1 in 2 or 1 in 3 chance have a good think and pick the most probable answer.

-Last of all review all your answers.

But the best thing you can do is revise, revise, revise. Read your notes over and over again, if you read a page and it hasn't sunk in read it again or until it does.

If your reading something you just can't get your head round it yourself on here and ask. Theres no such thing as a stupid question so ask anything and the guys on here will talk you trough it till you understand.

By coming on a forum like this you earn the respect from all the members because your making the effort to learn not just giving up.

Good luck with your studies, get them questions rolling in.

Tim

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this forum is probably the best tutoring you can get. ask away on anything your unsure of and someone will help

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thanks everyone i dont think anyway u can get a exzact answer for it so i am just going to go with the closest i have the answer paper here too so i will check it when i have done them all cheers everyone

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this forum is probably the best tutoring you can get. ask away on anything your unsure of and someone will help

Well put! Applaud Smiley

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Tim77 Is correct and AndyC is Half correct.

For AndyC to 100% Correct, he would have had to have said...

this forum IS the best tutoring you can get. ask away on anything your unsure of and someone will help

:D

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cheers everyone for your comments got the whole time free now till the exam which is on the 21st!! will be on here askin my questions !! 'The collages should tell everyone about this site! i will def reccomend it,

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hey have a questıon not sure ıf ı know the formulae and am readıng ıt wrong because when ever ı try ı never get the answers on ıt here ıt ıs .

A 33kV STAR connected 3-phase generator has a Phase Voltage of ?

11.01kV

57.16kV

33.1kV

19.05kV

thanks

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yeah i know i need to cheers mate :) i do revise alot and will continue are you a tutor or anything?? was wondering if you knew of any websites which are useful ??

AM I A TUTOR !!! Oh how wonderful !! Don't let my mate see that!! Thanks , Robbo! No M8 I'm an ancient Sparks who has been at it far too long, years of kneeling have buggered my knees and prolonged contact with builders has made me extremly cynical regarding the trustworthyness ( is that a word?) of the trade in general.

It now takes me twice as long to do things I did half as long at the same speed then as now , then. Eh!!

TUTOR !! I couldn't tutor my own backside if it was staring me in the face. :o

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Get on Google then type in Swindon Massive electrical.

That helps me immensely.

Fail 3 times and you have to repeat the year I believe.

(not to add any pressure)

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