Negative Voltage Regulation in Transformer

[QwertyXP]

How can a transformer have negative voltage regulation?
A few texts state that a leading power factor can give rise to negative power factor, but I have not been able to figure out how this is possible.

One vague explanation in my mind is that capacitance across the secondary terminal will somehow cancel out the leakage reactance on the primary side, thus resulting in a higher primary voltage and hence higher secondary voltage as well.

Can somebody please describe more accurately.

 

[UltrafastPED]

It means that your device is acting as a source of power; see:
http://en.wikipedia.org/wiki/Power_factor

and the "Talk"
http://en.wikipedia.org/wiki/Talk:Power_factor#Negative_Power_Factor.3F

 

[QwertyXP]

I think I've somewhat become used to the idea of negative voltage regulation after going through lots of articles and also drawing the phasor diagram myself. The main issue seems to be resolved now.

However, I still have confusions as far as the related calculations are concerned. For example, if you have a look at the following link:
http://yourelectrichome.blogspot.com/2011/07/voltage-regulation-of-transformer.html

According to example 1, full load current = KVA rating/secondary voltage specified in the question statement. Thus in this case, he has assumed 125V to be the full load voltage. However, in another place (part ii), he considers 125V to be the no load voltage while calculating the secondary terminal voltage.

Is this a mistake, or did he make this assumption because the value of current would not differ by too much even if no load voltage were used in the calculation?