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Current Transient in a Purely Inductive Circuit

Author: E.E. Kimberly

If the pure resistance of Fig. 8-1 be replaced by a hypothetical pure inductance, as in Fig, 8-2 (a), and the switch be closed, the only deterrent to current rise is the induced counter electromotive force in the inductance caused by the rise of current and hence rise of flux therein. The induced voltage must be constant, and the rise of current therefore must be constant. The induced voltage is


This voltage is negative because it is opposite in direction to the current in the circuit. The resulting current would rise as shown in Fig. 8-2 (b). The rate of current rise is inversely proportional to the inductance L.

Fig. 8-2. Rise of Current in an Inductive Circuit

Last Update: 2010-10-05