Page:Elementary lectures on electric discharges, waves and impulses, and other transients (Steinmetz 1911).djvu/17

 ₵condenser C is charged, the current in the line A and the condenser C is zero again. That is, the permanent condition before closing the switch S, and also some time after the closing of the switch, is zero current in the line. Immediately after the closing of the switch, however, current flows for a more or less short time. With the condition of the circuit unchanged: the same generator voltage, the switch S closed on the same circuit, the current nevertheless changes, increasing from zero, at the moment of closing the switch S, to a maximum, and then decreasing again to zero, while the condenser charges from zero voltage to the generator voltage. We then here meet a transient phenomenon, in the charge of the condenser from a source of continuous voltage.

2. Consider the simplest case: an electric power transmission (Fig. 3). In the generator G electric power is produced from mechanical power, and supplied to the line A. In the line A some of this power is dissipated, the rest transmitted into the load L, where the power is used. The consideration of the electric power