Circuitry for telecommunication, especially telephone exchanges with switching devices powered by a service voltage and an auxiliary voltage.

摘要

Individual switching devices powered by a service voltage are powered by one of two auxiliary voltage sources provided doubled for safety reasons. Switching from one of the two auxiliary voltage sources to the other one in accordance with the old version is done centrally but, in accordance with the novel version, in a decentralised manner. By comparison, universally usable switching devices are equipped with a monitoring device with the aid of which a distinction is made between the old version and the novel version and, when used in each of the two versions, the failure of the respective auxiliary voltage is monitored.