Detection of Inter-Turn Winding Short-Circuit Fault in Single-Phase Transformers

Is it because the shorted turn behaves as a low-pass filter?

The shorted turns are probably acting as a tertiary winding.

Thanks for the suggestion. I agree, the shorted turns definitely act as a tertiary winding whose power is being fed from the primary and the power is being dissipated in it as heat.

But how is it related to the increase of only the fundamental component of the no-load current ?

The shorted turns will be adding load which as you say in dissipated as heat. Acting as a tertiary winding the shorted turns will reduce harmonics.

The end result will be a lower percentage of the loading will be the high order harmonics. If I'm reading your question right it is the percentage difference that is concerning you.

Because to generate harmonics - you need a NON-LINEAR ELEMENT. Your do not have one - thus you have no added harmonics.

In my experience using high frequency testing in transformers, the sinusoidal signal waveform will be damped and its duration shortened when a winding short is present. It was also noted that even a partial winding short condition (not completely shorted winding) was detected, presented by a slightly dampen condition..

May I inquire as to why you are using your time up doing this? It would appear to be something that is seldom if ever needed.

In a practical environment, if a transformer has shorted windings or a short, the effects are usually obvious and a inductance meter reading compared to an identical unit (or note the both winding inductance values before installation) will quickly show if the unit is faulty or not and could also indicate the reason - if you wish to know why.

Unless you are into making the transformers up yourself (I've done that but many years ago and its not something I feel a need to repeat personally), the information as to why it's not working is often not very useful - it's broke, replace it....

Having a temperature sensor on the Trafo might have indicated an overload condition before permanent damage was done, which may point to something taking too much current and causing overheating, which probably indicates that the "follow-on" circuit has no method of detecting such errors = bad design.

In all the years in electrics and electronics that I have had (1955 to today), I have never needed or thought to have needed such software.

A good Multimeter was enough.

Can you demonstrate here for us just what practical advantages you will be achieving with this work?

Thanks for your answer.