Page:Canadian patent 24033.djvu/2

 TO ALL WHOM IT MAY CONCERN:—

Be it known that I, Nikola Tesla [formerly] of Smiljan Lika, Border country of Austro Hungary, [now residing in Rahway in the State of New Jersey, United States of America, Electrician,] have invented an Improvement in Dynamo Electric of which the following is a specification:—

The object of my invention is to provide an improved method for regulating the current on dynamo electric machines.

In my improvement I make use of two main brushes to which the ends of the helices of the field magnet are connected and auxiliary brush and a branch or shunt connection from an intermediate point of the field wire to the auxiliary brush. The relative position of the respective brushes are varied either automatically or by hand, so that the shunt becomes in-operative when the auxiliary brush has a certain position upon the commutator; but when said auxiliary brush is moved in its relation to the main brushes or the latter are moved in their relation to the auxiliary brush, the electric condition is disturbed and more or less of the current through the field helices is diverted through the shunt, or a current passed over said shunt to the field helices. By varying the relative position upon the commutator of the respective brushes automatically in proportion to the varying electrical condition of the working circuit the current developed can be regulated in proportion to the demands in the working circuit.

Devices for automatically moving the brushes in