CIRCUIT FOR TRANSFERRING CENTRAL OFFICE LINE WHEN POWER FAILURE OCCURS IN KEY PHONE SYSTEM

摘要

PURPOSE: A circuit for transferring a central office line when power failure occurs in a key phone system is provided to have a built-in PFT(Power Failure Transfer module) in a terminal strip, so as to transfer the central office line automatically to an extension subscriber of an optional general phone only by connecting a champ connection without connecting an additional jump wire. CONSTITUTION: A central office line card champ connector(10) of which one side is connected to a central office line card of a system is provided. A central office line champ connector(12) is connected to the central office line card champ connector(10) in parallel, and of which one side is connected to tip and ring terminals of a central office line and the other side is connected to a normal cross terminal of a relay switch. A subscriber card champ connector(14) of which one side is connected to an extension subscriber interface card of the system and the other side is connected to a normal open terminal of the relay switch is provided. A phone champ connector(16) of which one side is connected to tip and ring terminals of an extension phone and the other side is connected to a common terminal of the relay switch is provided. And a relay operating circuit connects the common terminal and the normal open terminal by responding to an input of a power voltage, and connects the common terminal of the relay to the normal cross terminal by cutoff of the power voltage.