How do you determine the flux density of a transformer?

The value of flux density is chosen to suit the guaranteed performance. Normally flux density is chosen near the knee point of magnetisation curve. However in some cases flux density value is reduced to limit the noise level of transformer.

What is the flux of transformer?

Flux is magnetic flux or a magnetic field created in the iron core of the transformer by the AC current flowing in the primary winding. A constantly changing magnetic field created by the AC applied to the primary is the means by which an AC voltage and current is induced in the secondary winding of the transformer.

Is flux constant in transformer?

The power transformer is a constant flux device because it follows the Lenz’s law, for every change in flux density caused by loading on secondary it will draw the magnetizing current proportionately from primary. So, the net flux in the core is always constant.

What is the leakage flux in a transformer?

Leakage Reactance of Transformer A small portion of flux will link either winding but not both. This portion of flux is called leakage flux. Due to this impedance of transformer, there will be voltage drops in both primary and secondary transformer windings.

What is saturation flux density?

Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density B more or less levels off. Different ferromagnetic materials have different saturation levels.

Does the flux in a transformer core increases with load?

NO, it does not increase with load over what it is at no load. At full load there is current flowing in the secondary winging in opposite direction to the primary winding, so the currents together cancel out each other leaving only the magnetizing flux to exist in the core.

How can we reduce the flux leakage in transformer?

Statement ( A ) : Flux leakage in a transformer can be minimized by winding the primary and secondary coils one over the other.

What is the maximum flux density of a BM transformer?

The maximum flux density Bm depends very much on the material used. Mains frequency transformer steels can be operated at least to 1.5 Tesla [15,000 gauss] – and probably up to 1.7 or 1.8 Tesla depending on the core losses and magnetizing current harmonics one is willing to tolerate.

What are the factors affecting the efficiency of a transformer?

It is further to be noted that, due to increase in maximum flux density of the core materials, the volt per turn of the transformer increases. Due to increase in volt per turn, the requirement of copper materials, insulations and cooling reduces considerably. All of these factors lead to better efficiency of transformer.

What is the function of a magnetic transformer?

A transformer is an electromagnetic machine used to transfer electric energy between two circuits through a varying magnetic flux. Transformers cores use ferromagnetic materials with a permeability much higher than the air. Their permeabilities vary with the flux density, and a given mmf produces a flux whose magnitude changes.

What is the flux density of a magnetic circuit?

The flux density Br at H = 0 is the residual magnetic flux density, and the magnetizing force Hc at B = 0 is the coercive force, required to reduce the residual magnetism to zero. During one complete cycle, the energy supplied to the magnetic circuit is higher than that returned to the source.