Relation between MMF and Flux of a Transformer

May 3 • General • 9473 Views • 2 Comments on Relation between MMF and Flux of a Transformer

A transformer is a two port device which transforms energy by inductive coupling between its winding circuit.It has a core that transforms current MMF from its primary circuit to its secondary circuit. The primary parameters are I1, E1, V1 and the secondary parameters are I2, E2, V2. A transformers are constructed in two types core type and shell type.more over transformer are of two uses one for step down voltage i.e from high voltage to low voltage and another is step up voltage i.e from loww voltages to high voltages. 

Relation between MMF and Flux of a Transformer :-

step up transformer

3 phase step up transformer

To know about relation between MMF and Flux of a transformer we have to know what is transformer,MMF and Flux.

TRANSFORMER:

The transformer is an electrical device which transfers energy by inductive coupling between its winding circuit.

MAGNETIC FLUX:

Magnetic flux is defined as the product of the average mangetic field times the perpendicular area.

MMF(Magnetomotiveforce):

Magnetomotiveforce is defined as the product of current flowing through the wire and the numbers of windings.

INDUCTION LAW:
There are basically two principles of transformer,

  • Magnetic field is produced by electric current.
  • Change in magnetic field within a coil of wire induces a voltage across end of of the coil
Transformer

practical transformer

When current passes through primary coil it creates a magnetic field and that magnetic flux passes through both primary and secondary coils.

Now from faraday’s law of induction,

VS=ES=NSd fi/dt

Where VS=ES=instantaneous voltage
NS is number of turns in secondary coil
dfi/dt is derivative of the magnetic flux through one turn of the coil

RELATION BETWEEN MMF AND FLUX:

FM=H.Le
H=Magnetic field strenght
Le=effective magnetic path length
Again FM=I.N
I=current flowing through wires
N=numbers of turns of coil
fi=V.T/N
V=voltage developed

fi=FM/RM

Rm=Reluctance
fi=2W/FM

where,W is Field energy in joules.

IMPORTANT QUESTIONS:

1. What is transformer?

Ans. The transformer is an electrical device which transfers energy by inductive coupling between its winding circuit.

2. What is magnetic flux?

Ans. Magnetic flux is defined as the product of the average magnetic field times the perpendicular area.

FM=H.Le

H=Magnetic field strenght
Le=effective magnetic path length
Again FM=I.N
I=current flowing through wires
N=numbers of turns of coil

3. What is the relationship between mmf and flux of a transformer?

Ans FM=H.Le

H=Magnetic field strenght
Le=effective magnetic path length
Again FM=I.N
I=current flowing through wires
N=numbers of turns of coil
fi=V.T/N
V=voltage developed
fi=FM/RM
Rm=Reluctance
fi=2W/FM
where,W is Field energy in joules

4. What is the expression for induction law for transformer?

Ans. VS=ES=NSd fi/dt
Where VS=ES=instantaneous voltage
NS is number of turns in secondary coil

5. What are the working principle of transformer?

Ans. There are basically two principles of transformer,

  • Magnetic field is produced by electric current.
  • Change in magnetic field within a coil of wire induces a voltage across end of of the coil

For more questions on Transformer one can refer to the below links:-

  1. Sample paper on transformer

For more topics on Transformer one can refer to the following:-

  1. SAMPLE PAPER ON ELECTRICAL MACHINE
  2. QUESTION AND ANSWER ON TRANSFORMER

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2 Responses to Relation between MMF and Flux of a Transformer

  1. Rajhana pandey says:
  2. Rachita Mishra says:

    This article is about Relation between MMF and flux of transformer.A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. A varying current in the primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic flux through the secondary winding.

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