Transformer formula

[mickys86]

Hi guys. Studying for my 301 and I'm not getting the transformer formula.
Vp/Vs = Np/Ns = Is/Ip

Then it keeps going on to say we can then transpose this to get....

Vs = Vp x Ns / Np
We also get Np = Vp x Ns / Vp

How are they using the first formula to get the others?
Please help. Thanks!
Michael

 

[Top Cat]

Glad i'm not at college anymore!

 

[mickys86]

TC I was really excited then I am searching my book and it shows no explanation of "transposing" this formula

 

[Silly Sausage]

Hi guys. Studying for my 301 and I'm not getting the transformer formula.
Vp/Vs = Np/Ns = Is/Ip

Then it keeps going on to say we can then transpose this to get....

Vs = Vp x Ns / Np
We also get Np = Vp x Ns / Vp

How are they using the first formula to get the others?
Please help. Thanks!
Michael

Michael, Simple algebra!

eg a/b = c/d

multiply both sides with b =>

(ba)/b = (bc)/d; the bs on the lhs cancel out =>

a = bc/d


Hope that helps (in a completely non patronising way )

 

[Top Cat]

Sorry to put your hopes up Micky. Take me longer to go through my old books than you! Wait until Tel gets on (after food and a beer) and he will sort you out!

 

[telectrix]

what does N represent?

 

[StuSpiers]

Number of turns i believe

 

[Top Cat]

what does N represent?

Nobed?

 

[mickys86]

N is number of turns. Np is primary turns and Ns is secondary turns

 

[telectrix]

OK, it's a simple ratio then. say you've got 2000 turns primary, and 200 turns secdondary, then the voltage ratio is 10:1. the current ratio is therefore 1:10. that's without considering PF and efficiency, of course. siimppless.

 

[MarkieSparkie]

Hi guys. Studying for my 301 and I'm not getting the transformer formula.
Vp/Vs = Np/Ns = Is/Ip

Then it keeps going on to say we can then transpose this to get....

Vs = Vp x Ns / Np
We also get Np = Vp x Ns / Vp

How are they using the first formula to get the others?
Please help. Thanks!
Michael

Hi Michael, Think of the original equation as a shorthand way of stating the relationships of the three equivalent transformer ratios. When you come to use the equation, you pick any two of the equivalent ratios and transpose that formula to obtain the parameter (subject) you want in terms of the other three.
Vp/Vs = Ns/Np or Vp/Vs = Is/Ip or Ns/Np = Is/Ip
Now try transposing these formulas making each parameter the subject of the equation in turn until you have all twelve possible combinations ... post you answers so we can help you with any that you struggle with.

 

[Knobhead]

From 4 values where three are given you can get 4 transpositions of any formula.

Use Google to look up formula transposition.

 

[mickys86]

Thanks very much. I'll have a closer look after tennis. I need to de-stress so going to take it out on a little green fuzzy ball for a couple of hours!!

 

[mickys86]

Hi guys just an update, I passed my 301 with a credit. I still don't get this but have been sooo busy haven't really had a chance to look into it. Your advice wasnt wasted, I will look into it!

 

[Top Cat]

Hi guys just an update, I passed my 301 with a credit. I still don't get this but have been sooo busy haven't really had a chance to look into it. Your advice wasnt wasted, I will look into it!

Glad to be of help Micky!:smilewinkgrin: