Till: TRANSFORMER 



173 



the coils and magnetic circuit are all stationary with respect to 

 one another. The electromotive forces are induced by the 

 ge in the magnitude of the flux with time. This is illustrated 

 iii Km. 170. 



A core is made up of rectangular stampings of sheet steel, 

 claniix'd or bolted together. 



A continuous winding P is placed on one side or leg of the 

 iron core. Another continuous winding S, which may or may 

 not have the same number of turns as P, is placed on the opposite 

 side or leg. An alternator A supplies current to the primary 

 winding P. As this winding is linked with an iron core, its 

 magnetomotive force produces an alternating flux in the core. 



Alternator 



Fio. 170. Simple transformer, secondary open-circuited. 



This alternating ilux links the turns of the winding N. As this 

 flux is alternating, it induces in the winding S an emf. of the same 

 frequency as its own. Because of this induced emf., the second- 

 nix winding S is capable of delivering current and energy. There- 

 rgy is transferred from /', the primary, to S, the 

 secondary, by means of the magnetic flux. 



Th- winding /' which receive* the energy is called the primary. 

 The winding >' which delivers the energy is called the secondary. 

 In a transformer, either winding may be the primary, the other 

 beinu the -ecomlary, deluding upon which winding receives 

 and which delivers energy. 



77. Induced Electromotive Force. The flux <, called the 

 mutual flux, in pas-inn' through the magnetic circuit formed by 

 the iron OOre, link- not only the turns of the secondary winding 

 N. but also It be primary winding /'. Theivfo: 



emf. must be induced in both th- windings >' and /'. As this 

 flux is the same for each hidings it must induce the 



