BusinessPhone Communication Platform 7.0
Installation Instruction ASB 150 02 > Boards for ASB 150 02

## Power failure circuit (PFC) on BTU‑A/BTU‑A2 and BTU-C

In the event of mains failure and if no back-up battery is connected to the PBX, a relay on the BTU-A and BTU-C boards (see under BTU-C on the previous page) automatically switches the trunk lines (generally 2) directly to the analogue telephones, if connected to this board.

If an ELU-A board is installed, these telephones can be used as common extension during normal operation but in case of power failure they will be automatically connected directly to the public exchange.

Revision: J © Ericsson Enterprise 2005