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The path of the magnetic flux in transformer should have
High reluctance
Low reluctance
High resistance
Low resistance
Low reluctance
The magnetic core of a transformer provides a closed path for magnetic flux to link the primary and secondary windings. To minimize energy losses and ensure efficient electromagnetic induction, this path must offer minimum opposition to the flow of magnetic flux, known as reluctance.
The magnetic core of a transformer provides a closed path for magnetic flux to link the primary and secondary windings. To minimize energy losses and ensure efficient electromagnetic induction, this path must offer minimum opposition to the flow of magnetic flux, known as reluctance.
S=╬╝AlтАЛ тАФ Formula for reluctance
╬ж=SFтАЛ тАФ Magnetic circuit Ohm's law equivalent
According to the analogy between magnetic and electric circuits, magnetic flux (╬ж) is driven by magnetomotive force (MMF or NI) against reluctance (S). The relation is ╬ж=SMMFтАЛ. To maximize flux for a given MMF, the reluctance S=╬╝AlтАЛ must be kept as low as possible. This is achieved by using ferromagnetic materials with high permeability (╬╝) and designing a path with short length (l) and sufficient cross-sectional area (A).
High permeability materials like CRGO (Cold Rolled Grain Oriented) steel are used to keep reluctance low.
Low reluctance minimizes the magnetizing current required to produce the flux.
The air gap in a transformer core is intentionally minimized or eliminated to prevent high reluctance.
Magnetic reluctance is analogous to electrical resistance in an electric circuit.
Reduces magnetizing current requirement
Improves transformer efficiency
Enhances flux linkage between primary and secondary windings
Low reluctance paths can be heavy due to the amount of iron required
High cost of high-permeability magnetic materials
Power transformers
Distribution transformers
Inductors and reactors
The SI unit of reluctance is Ampere-turn per Weber (AT/Wb).
Option A is incorrect because high reluctance would require a much higher magnetizing current, leading to high copper losses and poor power factor.
B is correct тАФ The path of magnetic flux in a transformer must have low reluctance to facilitate efficient flux flow and reduce magnetizing current.
Always remember the analogy: MMF тЖФ EMF, Flux тЖФ Current, and Reluctance тЖФ Resistance. This makes magnetic circuit analysis identical to DC circuit analysis.