THE TRANSFORMER. 



217 



of the General Electric Company. The essential features of this 

 transformer are shown in Fig. 180, in which CCC is the lami- 

 nated iron core, PP is the stationary primary coil, and 55 is 

 the secondary coil which is suspended from a counterpoised lever 

 system so as to move up and down with great ease. When lamps 

 are short-circuited, the slight increase * of current causes an in- 

 creased repulsion between P and S, the coil 5 moves up- 

 wards, and the increase of leakage flux across the regions LL 

 lessens the useful flux through the secondary coil S, which re- 

 duces the induced voltage in S, thus counteracting the tendency 

 for the current to increase. 



108. Simple tranformer connections. Connections in parallel. 

 Connections in series. When transformers are used to supply 

 current to groups of lamps or motors at constant voltage, step- 

 ping down from constant voltage transmission lines, the primary 



main 



Fig. 181. 



of each transformer is connected directly across the high voltage 

 mains and each transformer delivers current to a separate group 

 of lamps or motors as shown in Fig. 181. This arrangement is 

 called the parallel connection of transformers. 



* An initial increase of current must be produced in order to start the moving coil 

 upwards, but the lever system may be so designed as to keep the equilibrium value 

 of the current almost exactly constant with decrease of resistance of receiving circuit, 

 or even to cause the equilibrium value of the current to decrease with decrease of re- 

 sistance of receiving circuit. 



