THE TRANSFORMER.
Usually the electric fluid (?) is conveyed into the building from the alley, where the high tension wires are strung, carrying a pressure of 2,500 to 3,500 volts from this line. By the aid of a “transformer” the current is reduced to a pressure of 110, 105 or 50 volts, as required, entering the building, when it is conveyed to a double-pole switch; that is, a switch which cuts off both positive and negative wires at the same instant.
The “transformer” is a device for reducing the current from one potential or tension to another, and consists of a ring of many turns of insulated wire; the high tension wire is then wound around and through this ring several turns, and the low tension wire carrying the current into the building is wound around the opposite side of the ring in like manner. The difference in pressure is controlled by the number of turns around the ring on either side, as shown.
All the wires being insulated, the reduction is made by “induction” only. The size of the wire makes no difference in the voltage or pressure, but it makes all the difference in the “amperes” or quantity used to supply the building.
The electric light company will supply a sufficiently large wire from transformer to switch; the firm does the remainder of the wiring.