While comparing potential transformer to an auto transformer, a potential transformer transfers power ________
Potential divider is resistance division and it does not take part in induction processes.
The statements which support the points that auto transformers are advantageous
I. Weight of conductor reduces
II. Ohmic losses reduces
III. Leakage reactance reduces
IV. Lower shortcircuit current
Short circuit current of the auto transformer is higher than the corresponding 2winding transformer
The statements which support the points that auto transformers are disadvantageous as compared to 2winding transformer
I. Weight of conductor reduces
II. Direct electrical contacts
III. Leakage reactance reduces
IV. Lower shortcircuit current
Direct electrical contacts is a disadvantage to the auto transformer.
Short circuit current of the auto transformer is higher than the corresponding 2winding transformer.
I. KVA rating : 1/(1k)
II. Losses : (1k)
III. Impedance drop = 1/(1k)
Which of the above are correct for an auto transformer when compared to the identical rating two winding transformer?
KVA(auto)/KVA(2W) = V2*I2/V2*(I2I1)
= 1/(1I1/I2)
= 1/(1k)
Losses(auto)= (1k) *Losses(2W)
Impedance drop(auto)= (1k)*Impedance drop(2W).
The voltage regulation of a transformer at fullload 0.8 p.f leading is 2%. Its voltage regulation at full load 0.8 p.f lagging
The leading p.f. has negative v.r. and lagging p.f. has major portion of positive voltage regulation.
The voltage regulation of a transformer is not dependent on its
Voltage regulation is independent of the size of the transformer.
Three transformers having identical dimensions but with core of iron, aluminium and wood are wound with same number of turns and have same supply.Then choose the order for hysteresis losses.
Hysteresis losses occur maximum in the ferromagnetic material.
Maximum efficiency of a transformer for a constant load current , occurs at
Efficiency = KVA*p.f/(KVA*p.f + Losses); So the efficiency is maximum at unity power factor.
A 1phase tranformer has a leakage impedance of 1+ j4 Ω for primary and 3+ j11 Ω for secondary windings. This transformer has
The side which has lower impedance will have lower number of turns and so the low voltage side.
If a transformer is at no load , then it will act like
Transformer is nothing but the arranged windings which are magnetically coupled. The windings will inductive predominantly with very low resistance.
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