Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Transformer Math Check

Status
Not open for further replies.

ITT-Joe

New Member
I've got a question regarding transformer math. I would like someone else to confirm that I have the concept correct as I'm a tad bit confused and the many books and online content I've covered does not explicitly state what I'm asking.

(By the way, yes, this is my first post. I just found this forum and after having a look around, I decided to register. Think of this as my introduction, sort of.)

Anyway, the way I understand math related to transformers is this;

Voltage Primary (Vp) over Voltage Secondary (Vs) is equal (=) to Number of Turns Primary (Np) over Number of Turns Secondary (Ns).
(Vp over Vs = Np over Ns)

So if I have a transformer with an unknown Vp, an Vs of 25 volts, an Np of 20, an Ns of 100. The Vp (or voltage primary) would be 5 volts, correct??
(Vp = ??, Vs = 25v, Np = 20, Ns = 100)

Hopefully you understand this. If not, I'll draw up a quick diagram to perhaps make it more clear, as typing fractions is not possible. Thank you in advance for the assistance in clearing up my confusion.
 
Last edited:
Sounds about right...

A page from a class at school....
8978-dsc06794.jpg
 

indulis

New Member
Yes, in a transformer the primary and secondary voltages and currents are proportional to the turn’s ratio.

Np/Ns=Vp/Vs=Ip/Is

However, that’s for an “ideal transformer” and real world transformers are not “ideal”. You have copper loss, core loss, coupling coefficients, leakage inductance… etc. to take into consideration.
 

Mathieu3545

New Member
Yes, in a transformer the primary and secondary voltages and currents are proportional to the turn’s ratio.

Np/Ns=Vp/Vs=Ip/Is

However, that’s for an “ideal transformer” and real world transformers are not “ideal”. You have copper loss, core loss, coupling coefficients, leakage inductance… etc. to take into consideration.

CORRECTION: The ratio is

Np/Ns=Vp/Vs=Is/Ip
 

ke5frf

New Member
You have it.

Understanding transformers is no different than understanding gear reduction or multiplication, even so much as the effect each step-up or down has on reversing current flow is analogous to the gears turning in opposite directions.
 
Status
Not open for further replies.

EE World Online Articles

Loading
Top