USING SMATH STUDIO FOR SOLVING A SIMPLE ELECTRICAL ENGINEERING PROBLEM

OBJECTIVE

In despite of the software limitations, Smath Studio is an excellent tool for solving Engineering Electrical Calculation.

In this article, I solve a single-phase transformer problem using the Smath Studio.

For this kind of calculation, a limitation of this software is there is no Ampere/turns unity, but it's possible to use Ampere and noting some outputs are in Ampere per turn.

PROBLEM FROM "Electrical Machines and Systems Drive Third Edition (John Hindmarsh Alasdair Renfrew)

A 20-kVA, 3810/230-V, 50-Hz single-phase transformer operates at a maximum flux density of

1.25 teslas, for which the iron requires a value of H = 0.356 At/mm. The core cross-section

is 0.016 m ~ and the mean length of the magnetic path through the core is 1.4 m. The primary

and secondary turns are 860 and 52 respectively. It is decided to use the transformer as an

inductor and to keep the reactance substantially constant with current, the core is sawn

tl- rough transversely and packed with brass to give an 'air' gap. If the secondary winding is

u, t d , find the length of the air gap so that when carrying rated current, the maximum flux

density is not exceeded. What is then the inductance and the reactance at 50 Hz?

Solving for 60Hz:

NOTES:

1. When the frequency of the power increases, the reactance increases too. In due of this, is very dangerous feed a 60Hz Motor with 50Hz power supply. The Electrical current will increases in function of the reactance decrease, increasing the temperature and some other features of the motor what depends of the frequency of feeding.
2. Don't forget about mention, by text box, the "Ampere per turn", to mitigate any mistake.

REFERENCE

Electrical Machines and Systems Drive, Third Edition, John Hindmarsh BSc (Eng), CEng, MIEE Formerly Senior Lecturer, University of Manchester Institute of Science and Technology and Alasdair Renfrew BSc, PhD, CEng, MIEE Senior Lecturer, University of Manchester Institute of Science and Technology Newnes Books