## Questionnaire

### FAQ

What is a Transformer ?

A transformer is a static electrical device which electro-magnetically transforms AC voltage

What is meant by Transformer engineering ?

Transformer engineering is a branch of electrical engineering. It is the art of getting desired voltage transformation from AC source. Its manifestation is conforming to Faraday's laws of induction and it is related to Maxwell's field theory. it is based on both the search of facts and the adventure of new ideas. The function is based on experimental and practical evidence

What is Transformer action ?

The fundamental studies of AC inductances is basic in AC circuits concepts. When two coils of wire are inductively coupled, the magnetic flux that passes through one coil, pass through the other to a greater or lesser degree. In the other words, magnetic circuit is commonly or largely common to both the coils. If the mutual flux is cyclically varying because the coil that creates a cyclically varying current in it, the magnetic flux linkage to the second coil is also cyclically changing. As a result, the varying flux generates a secondary varying voltage in the second coil. The secondary voltage is said to be created by the transformer action.

What exactly is a transformer ?

• A simple device / equipment
• Reliable in service
• Convenient to operate & maintain
• Transfers electrical energy from one circuit to another
• Does so without change of frequency
• Does so by principle of electromagnetic induction
• Electric circuits are linked by a magnetic circuit
• Troubles are rare

What is mutual induction ?

When the magnetic field is linked with a circuit, changes in a e.m.f will be induced in the circuit. Mutual induction refers to the induction of an e.m.f in conductors in the vicinity of the other conductor in which the current changes in time. If the variation of current in one of two separate circuit sets up an induced e.m.f in the other, the two circuits are said to be inductively coupled, and the induced e.m.f is called e.m.f of mutual induction

What is magnetic circuit and its parameters ?

Magnetic circuit is a closed path by the magnetic flux in an electrical machine Core. Magnetic circuits care characterised by the following parameters

• Magnetic Flux = Phi ( Webers)
• Magnetic Induction or Magnetic Flux Density = Wb / Sq.M = Tesla
• Magnetic intensity or magnetic field strength = H Ampere / m
• Magneto Motive Force (MMF) = IN ( Ampere Turns)
• Reluctance = A / Wb
• Permeance ( the reciprocal of reluctance) = Wb / Ampere

The magnetic circuit presents a magnetic opposition, known as reluctance, which depends on the circuit length, the core cross sectional area, and the permeability of the core material. The core should offer low reluctance so that, the magnetising current to establish flux is as less as possible. Further the core should lead to low core loss and possess high degree of saturation. the retentivity should be as less as possible.

Magnetic Circuit major parameters

Magnetic property : The magnetic field at a point is numerically equal to the force on a unit positive change moving through the point in a direction perpendicular to the field with unit velocity

Magnetic Lines of force : The magnetic lines of force are the imaginary lines drawn along the path taken by a magnetic needle placed in the field or in other words magnetic line of force is a curve drawn in a magnetic Reach Us
T. Ram Prakash (Partner)
Procon Controls