BusinessPhone Communication Platform 4.0
Installation Instruction ASB 150 02 > Boards For ASB 150 02

## Power failure circuit (PFC)

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 (see under BTU-C on next page) board automatically switches the trunk lines (generally 2) to analogue telephones, if connected to this board.

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

#### Earth connection on BTU-A2 (Austria only)

Some markets require an earth connection of the incoming PTT earth (functional earth) to the exchange. This is provided on the connector installed above the PFC circuit connector on pins A22, A24, C22 and C24. Use an extra Krone bar to connect the PTT earth wires to the wires going to the board connector.

Revision: A © Ericsson Enterprise 2003