01․ Iron loss in a transformer mainly occurs in
Iron loss is also called core loss in transformer which consists of hysteresis loss and eddy current loss. Both of these losses associated with transformer core.
02․ Short circuit test is performed on a transformer with a certain impressed voltage at rated frequency. If the short circuit test is now performed with the same magnitude of impressed voltage, but at frequency higher than the rated frequency then
Since frequency has been increased, the leakage reactance and hence impedance will increase. Thus current will be less and power factor will be poorer.
03․ In a transformer the magnetic coupling between the primary and secondary winding can be increased by
Magnetic coupling between two windings depends upon flux linkage between them. Flux linkage can be maximized between two coils by placing magnetic core of low reluctance in between them.
04․ The short circuit test on a transformer is conducted to obtain
The watt meter reading in short circuit test of a transformer, gives the copper losses and negligible amount of core losses of the transformer. Since, the core losses depend upon applied voltage and voltage applied in short circuit test, is very small compared to rated voltage of transformer. Therefore, from the watt-meter reading in short circuit test, we get mainly copper losses of transformer.
05․ An auto transformer having a transformation ratio of 0.8 supplies a load pf 10 KW. The power transfered inductively from the primary to secondary is
If transformation ratio were, whole power would have been transfered conductively only. Power transferred inductively
[math] = Total \; power imes \left(1 - rac{N_2}{N_1}
ight) = 10 imes (1 - 0.8) = 2 \; KW. [/math]
[math] = Total \; power imes \left(1 - rac{N_2}{N_1}
ight) = 10 imes (1 - 0.8) = 2 \; KW. [/math]06․ In one 132 / 33 kV transformer the LV resistance is 0.02 per unit. The resistance referred to HV side is
The per unit value of any parameter of a transformer remain same irrespective of whether it is referred to primary or secondary.
07․ Lamination of transformer core is made of
The lamination of transformer core is made of cold rolled grain oriented silicon steel (CRGO silicon steel) to reduced its hysteresis loss.
08․ Oil is provided in an oil filled transformer for
Transformer insulating oil is used in transformer for both cooling and insulating purpose.
09․ Air core transformer as compared to iron core transformer, has
Magnetic core losses consist of hysteresis loss and eddy current loss. Hysteresis loss is associated with ferromagnetic property of iron and eddy current loss is associated with conducting property of iron. As the air is not a ferromagnetic substance as well as it is not a conductor so there will not be any core loss in the air core transformer.
10․ CRGO steel is used in the core of transformer to reduce
CRGO means cold rolled grain orientation. Hysteresis loss mainly occurs in ferromagnetic material due to its random grain (small magnetic region) orientation. In CRGO steel these grain are properly oriented so that hysteresis loss can be minimized.
<<<99100101102103>>>
