In this paper one considers a model representing a two‐unit identical system with one unit operating online, and the other unit in warm standby. The online unit is controlled by a protective unit which protects the online unit from any damage occurring. The online and protective units may fail due either to a hardware failure or to a shock failure. The failure and repair rates for the online, standby and protective units are constant but different. Expressions for the time‐dependent availability, steady‐state availability, reliability, mean time to failure and profit function are obtained by the Laplace transform technique. Finally graphs are also drawn for the above model to illustrate the various characteristics obtained. Some applications of the model are also given.