Electrical Engineering is a free introductory textbook to the basics of electrical engineering. See the editorial for more information....

Direct-Current Transients

Author: E.E. Kimberly

If a switch is caused to close in a hypothetical circuit containing a battery, a switch, and only unvarying resistance, as in Fig. 8-1 (a), the current will rise instantly to its ultimate or steady-state value, which is


There will be no transient when the switch is closed or when it is opened. If, however, the resistance is not constant but varies with its temperature, there will be a current transient which will subside only when the temperature has reached its ultimate value. Fig. 8-1 (b) shows such a transient current in a lamp which has a filament with a perceptible inductance.

Fig. 8-1. Current Transient Caused by Temperature Change in an Incandescent Lamp Filament When the Circuit Is Closed

Last Update: 2010-10-05