A 2V/1V two- winding transformer is connected as an autotransformer. I...
Autotransformer and Two-Winding Transformer
Before explaining the voltage regulation of a 2V/1V two-winding transformer as an autotransformer, let's first understand the difference between an autotransformer and a two-winding transformer.
- An autotransformer has a single winding that acts as both the primary and secondary winding.
- A two-winding transformer has separate primary and secondary windings.
Voltage Regulation
The voltage regulation of a transformer is defined as the change in secondary voltage from no-load to full-load expressed as a percentage of the full-load voltage. It is given by the formula:
% voltage regulation = (V_no-load - V_full-load) / V_full-load x 100%
Autotransformer Voltage Regulation
When a two-winding transformer is used as an autotransformer, one winding is used as both the primary and secondary winding. In this configuration, the voltage regulation is much better than a two-winding transformer.
The voltage regulation of an autotransformer is given by the formula:
% voltage regulation = (V_no-load - V_full-load) / V_full-load x 100% = (V_in - V_out) / V_out x 100%
Since the input voltage (V_in) and output voltage (V_out) are almost the same in an autotransformer, the voltage regulation is low.
Two-Winding Transformer Voltage Regulation
The voltage regulation of a two-winding transformer is given by the formula:
% voltage regulation = (V_no-load - V_full-load) / V_full-load x 100% = (V_1 - V_2) / V_2 x 100%
where V_1 is the voltage applied to the primary winding, and V_2 is the voltage across the secondary winding.
Since V_1 is much higher than V_2, the voltage regulation is high in a two-winding transformer.
Comparison of Voltage Regulation
As we can see from the above formulas, the voltage regulation of an autotransformer is much lower than that of a two-winding transformer. In fact, the voltage regulation of an autotransformer can be up to three times better than a two-winding transformer.
Therefore, the correct answer is option 'D', i.e., the voltage regulation as an autotransformer compared to the two-winding transformer is three times better.
A 2V/1V two- winding transformer is connected as an autotransformer. I...
The answer is wrong , firstly Remember that Voltage regulation is better if it is lower , not higher , A voltage regulation of 3% is better then 5% .
Now Advantage of auto transformer is that it has Better V regulation then 2 phase transformer . So it is obvious that it should be not in any multiple of V regulation of two phase transformer . Hence the answer given is Technically wrong , you just can't have Auto transformer whose V reg is worse then 2 phase transformer it is made up of .
and if you want practical explanation then V reg of AutoXformer = (1-K) of 2 phase
Put K = 2/3 , 1/3 both values you will get = (1-2/3 ) and (1-1/3) in both of them value is 1/3 and 2/3 times Vreg of 2 phase
So answer is wrong , and wrongly said right in everywhere on internet .
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