Directions (Q. No. 11 to 15): |
Read the following text and answer the following questions on the basis of the same: |
Losses of transformer |
There are 4 types of losses in a transformer: |
Core loss, Ohmic loss. Stray load loss and dielectric loss. |
(1) Core loss |
Core loss has two components - hysteresis loss and eddy current loss. These together are called no-load losses of a transformer and are calculated by open circuit test. |
Hysteresis loss: This loss mainly depends on the core material used in the transformer. To reduce this loss, the high-grade core material can be used. CRGO- Cold rolled grain oriented Si steel is commonly used for this purpose. |
Eddy current loss: This loss can be reduced by designing the core using slight laminations. |
These losses are present even when no load is connected. So, these are also known as no-load loss. |
(2) Copper Loss |
Copper losses occur because of the Ohmic resistance in the windings of the transformer. If the currents in primary and secondary windings of the transformer are \[{{\operatorname{I}}_{1}}\] and \[{{\operatorname{I}}_{2}}\], and if the resistances of these windings are \[{{\operatorname{R}}_{1}}\] & \[{{\operatorname{R}}_{2}}\] then the copper losses that occurred in the windings are \[{{I}_{1}}^{2}{{\operatorname{R}}_{1}}\] & \[{{I}_{2}}^{2}{{\operatorname{R}}_{2}}\] respectively. So, the entire copper loss will be |
\[{{I}_{1}}^{2}{{\operatorname{R}}_{1}}+{{I}_{2}}^{2}{{\operatorname{R}}_{2}}\]. |
This loss is also called variable or ohmic losses because this loss changes based on the load. |
(3) Stray Loss |
These types of losses in a transformer occur because of the occurrence of the leakage flux. As compared with copper and iron losses, the percentage of stray losses are less, so these losses can be neglected. |
(4) Dielectric Loss |
This loss mainly occurs within the oil of the transformer. Oil is an insulating material. Once the oil quality in the transformer deteriorates then the transformer's efficiency is affected. |
Efficiency of Transformer |
It is the ratio of output power and input power. |
Efficiency = Output Power / Input Power. |
The transformer is a highly efficient device which ranges between 95% - 98.5%. |
A) Eddy current loss = Core loss + Hysteresis loss
B) Core loss = Hysteresis loss + eddy current loss
C) Hysteresis loss = Core loss + eddy current loss
D) Core loss = Hysteresis loss X eddy current loss
Correct Answer: B
Solution :
Option [b] is correct.You need to login to perform this action.
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