ENGINEERING.WEB

Transformer Construction The construction of a transformer is simple since there are no moving parts (i.e. it is a static device). The transformer shown in figure below consists of the following main parts: (i) Magnetic core (ii) Windings (iii) Conservator tank (iv) Transformer oil (v) Radiators (vi) Bushings (vii) Breather (viii)Container (ix) Buchnolz relay (i) Magnetic core: It is made of thick silicon steel laminations coated with oxide layer to reduce the iron losses. The thickness of lamination is 0.35mm for 60Hz operation and 5mm for 25Hz operation. It is the common part between the twowindings and helps to link magnetic flux with both the windings. (ii) Windings: A conventional transformer has two windings. The winding whichr eceives the electrical energy is called the primary winding and the winding which delivers the electrical energy to the load is known as secondary winding. The two windings are electrically separated but magnetically coupled through themagnetic core. The w...

 Working Principle of a Transformer A transformer is a static device which transfers electric energy from one circuit to another circuit without changing the frequency of the system. It works on principle of Faraday’s law of electromagnetic induction. According to this principle, an e.m.f. is induced in a coil if it links with a changing flux. Symbolic representation Arrangement of a simple transformer Transformer consists of two windings insulated from each other (i.e.electrically separated) and wound on a common core made up of magnetic material of low reluctance as show in figure (3.1). The winding which is connected to the supply is known as primary winding and the other winding to which the load is connected is called secondary winding. When the primary winding is connected to an AC supply, an alternating current flow through it. This current in the primary winding sets up an alternating flux (Ф) in the core, which completes its path in the common magnetic core as shown in the...

  DC Machine construction 1. Pole Body:  • It is made up of Silicon steel laminations.  • The laminations are piled one over another and tightened with bolts and nuts.  • Pole body is attached to yoke by counter sunk screws.  • It supports pole shoe and field winding provides low reluctance path. 2. Pole Shoe : • Made up of Si Steel laminations.  • Attached to pole body.  • Supports field windings.  • Helps in uniform distribution of flux in air gap. 3. Field Winding: • Made of copper conductors over which cotton tape is wound and impregnated in insulating oil and dried.  • On each pole body one field winding is kept and all windings are connected in series so as to make one field winding.  The sense of the windings are kept such that alternately N and S poles are produced around the periphery of the machine. • It is excited by supply voltage and produces the necessary working flux in them achine. 4. Armature: • It is made up of Si St...

Ohm’s Law It states that, at constant temperature, in an electrical circuit, the current passing through a conductor, from one terminal point on the conductor to another terminal point on the conductor, is directly proportional to the potential difference (voltage drop or voltage) across the two terminal points. V α I -> V = RI where R = resistance of the conductor. V= voltage I= current