Core type transformers have, LV and HV windings are arranged such that

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Examoogle · Accepted Answer

Half LV near the core and half HV outside LV on each limb

Explanation: In core-type transformers, the Low Voltage (LV) winding is placed nearest to the core to reduce the insulation requirement and the size of the core window. The High Voltage (HV) winding is placed over the LV winding with suitable insulation between them, a construction known as the concentric winding arrangement.

Working Principle: Placing the LV winding near the core significantly minimizes the insulation thickness between the winding and the earthed magnetic core, leading to a more compact and cost-effective design. Since leakage reactance is proportional to the square of the number of turns and the space between windings, this concentric arrangement keeps the leakage flux path small, reducing total leakage reactance.

Key Formulas: $L_l \propto N^2 \cdot d$; $\Phi_l = \frac{F}{R_l}$

Key Points: LV winding is placed closer to the core to minimize insulation cost.; HV winding is placed outside LV to provide easier access to connections and insulation.; This arrangement results in lower leakage reactance compared to separating them.; Insulation layers are placed between the core and LV, and between LV and HV.

Advantages: Reduced amount of expensive insulation required for the LV winding.; Improved mechanical strength and easier handling of connections.; Lower leakage reactance, leading to better voltage regulation.

Disadvantages: Requires high-quality insulation between LV and HV layers.; More complex winding manufacturing process compared to simple side-by-side arrangement.

Applications: Distribution transformers; Power transformers

Additional Info: The core-type construction is preferred for high-voltage, low-current applications.. Option B is incorrect because placing HV and LV on different limbs would result in high leakage flux and poor efficiency.. Option D describes 'Sandwich' windings, which are characteristic of Shell-type transformers, not Core-type.

Answer: A is correct — The LV winding is positioned closest to the magnetic core to minimize the insulation volume required between the conductor and the core.

Exam Tip: Always remember: 'LV near the Core' is the golden rule for cost-effective transformer design; it minimizes the insulation thickness between the low-potential winding and the grounded core.

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