Continue to Site

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 short circuit test question

Status
Not open for further replies.

windozeuser

Member
I have a question about the short circuit test of a transformer. If you perform the short circuit test and obtain the R equivalent and X equivalent values, are these the R(primary) and R(secondary) along with X(primary) and X(secondary) combined?

for example if Req was 400 and Xeq was 500, that would mean R primary was 200 ohms, and X primary was 250 ohms, and R secondary was 200 ohms, and X secondary was 250 ohms?
 
In a short circuit test, the resistance seen is the primary resistance plus the turns ratio squared times the secondary resistance.

In your example, the 400 ohms would only be split equally if the turn ratio were 1:1 and the primary and secondary were identical. Transformers often have a many more turns on one winding than the other, and the winding with more turns will use thinner wire. However you can't tell how much of the resistance comes from the each winding easily.

In mains isolation transformers with dual secondary windings, the two secondaries will often have different resistances but the same number of turns, as one is wound around the outside of the other, so is bigger diameter.
 
Primary purpose of this test is to find out leakage inductance. It can be done for primary and/or secondary. Depends on what you want to use the result for. Most common is to reference leakage inductance to primary side. (short secondary) Usually Rs is smaller compared to leakage inductance reactance value. If you're using an impedance meter you will get both R & XL values.

There is likely more inaccuracy due to not being able to drive core to full operating flux levels with a shorted winding.
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top