To obtain B-H curve of a magnetic materials.

Experiment Number: 15

AIM OF THE EXPERIMENT : –

                    To obtain B-H curve of a magnetic materials.

APPARATUS REQUIRED: –

Sl. No.NameSpecificationQuantity
1Single Phase Auto Transformer ( Variac)5KVA, (0-270) V1 Nos.
2Voltmeter(0-250) V, MI1 Nos.
3Voltmeter(0-150) V, MI1 Nos.
4Ammeter(0-2) A, MI1 Nos.
5Connecting WirePVC Insulated CopperAs per Required
Table No. : 8.1

CIRCUIT DIAGRAM: –

THEORY: –

When a Magneto motive force is applied to a homogeneous iron ring or core, a magnetic potential gradient is produced within the material and i.e expressed by H= (N*I)/l (where, H is magnetic field intensity or magnetic field strength, N is the number of turns of coil, I is the current supplied and l is the mean length of core).

from the above expression we may write H ∝ I ………… (i)

as l and N are constant quantity.

From faraday’s law of magnetic induction, we can write, induced emf (e) = – N*(dɸ/dt)….. (ii)

Since the supplied voltage is sinusoidal, the core flux is given by ɸ = ɸmsin 𝛚t and substituting the value in equation (ii) , we may get

\[\color\red{e}\;\color\green{ =}\;\color\red{ -N*{\dfrac{d(ɸ_msin𝛚t)}{dt}}}\] \[\color\green{ =}\;\color\red{ N𝛚ɸ_m \;Cos𝛚t}\] \[\color\green{ =}\;\color\red{ N* 2πf ɸ_m Cos 𝛚t}\] \[ \color\green{then,}\] \[\color\red{\; E_{max},}\color\green{\; when}\color\red{\; Cos 𝛚t = 1}\] \[\color\green{thus,}\] \[\color\red{\; E_{max}}\color\green{ =}\color\red{ 2πfN ɸm }\color\magenta{\;volt}\] \[\color\green{ dividing \;both \;sides \;by,}\color\red{\;\sqrt{2}}\] \[\color\red{E_{rms} }\color\green{=}\;\color\red{ 4.44fB_{max}AN }\color\magenta{\;volts,}\;\] \[\color\green{where,}\color\red{\; ɸ_m }\color\green{=}\color\red{ B_{max} A} \] \[\color\red{B_{max}}\color\green{ \;is \;flux \;density\; in}\color\magenta{\; wb/m^2} \]

The above expression may be written as Erms ∝ Bmax ….. (iii)

Thus a graph of V-I can be drawn by taking the respective data of V and I.

This curve is similar to B-H curve.

PROCEDURES: –

  1. All Instruments are connected as per circuit diagram shown in fig.
  2. The voltage is increased gradually by single phase auto- transformer & corresponding readings of Voltmeters & Ammeters are filled in observation table.
  3. Draw a graph of V1 and I which will show the relation between B and H parameters.

PRECAUTIONS: –

  1. Don’t switch on power supply without concerning teacher.
  2. Single phase autotransformer must be kept at minimum potential point before switch on the experiment.

OBSERVATION TABLE: –

Sl. No.I (in amps.)V1 (in volts.)V2 (in volts.)
1
2
3
4
5
6
7
8
Table: 8.2

CONCLUSION:-


To be written by student.

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