I902. No. II. ON A NEW ELECTRIC CURRENT BREAKER. 7 



energy is desirable. Thus the breaking off of the secondary current is 

 managed very quickly. 



Let us see how the transformer-like inducting system may serve to 

 extinguish the spark, and prevent the formation of an arc, by the 

 breaking off of intense currents of high tension. 



The main current to be broken is assumed originally to pass outside 

 the transformer, of which the primary coil stands in a shunt, as in the 

 inducting system in the case first described. 



As soon as the main circuit is opened, the secondary current is 

 closed and at the same time the entire main current tends to run through 

 the primary coil of the transformer. In the mean time the core of the 

 transformer remains non-magnetic, the proportion between the primary 

 and secondary coils being, as already mentioned, thus arranged. Conse- 

 quently the currents very quickly arrive at their maximal value, and 

 having reached it, they are both rapidly broken almost simultaneously 

 in such a way that the numerous secondary contacts are opened a 

 moment earlier than the main contact in the middle of the ebonite plate 



The weak secondary current has a tendency to stop instantane- 

 ously, owing to the numerous places of breaking. The primary current 

 must then magnetise the core of the transformer, thereby causing a 

 considerable electromotive counter-force in the primary coil, a force 

 which tends to arrest the primary current, while in the secondary coil 

 an extra current arises, running in the same direction as the disappearing 

 secondary current. 



In this way, the energy of the primary current at the moment of 

 breaking is consequently transferred by induction to the numerous secon- 

 dary places of breaking, where an intensified igneous phenomenon will 

 take place, which will not, however, injure the contacts. 



One condition necessarry to the occurrence of the phenomenon in 

 the above-mentioned manner, is that the core of the transformer shall 

 be of sufficient size, and further that it is of soft iron, and in shape an 

 unbroken ring. After being magnetised by the primary current at the 

 moment of breaking, it will retain the magnetism acquired as remanent. 

 At the next breaking of the current, therefore, the primary and secondary 

 currents of the transformer must both be the reverse of what they were 

 at the preceding breaking of the current. Instead of commuting the 

 poles in the primary and secondary coils before each entrance of the 

 currents in the inducting system, it will be more practical to let the 

 current in the secondary coil have a slight predominance over the primary 

 current, so that the iron core will be magnetised in the direction in 



