Emergency power supply

摘要

A subscriber circuit (TL) connected via an optical waveguide (LWL) in a broadband integrated services digital network, B-ISDN, has a first device (E1) for telecommunications services of a first type and a second device (E2) for telecommunications services of a second type. The first and second devices (E1, E2) are respectively connected via a first and second rectifier units (GR1, GR2) to a mains voltage transformer unit (NW) and thereby to the power mains. Furthermore, the first device (E1) is connected to an emergency power supply unit (NV). When emergency power is required, only the first device (E1), which comprises, for example, a telephone unit, is supplied with emergency power through disconnection of the power supply by means of the first and second rectifier units (GR1, GR2).