Instruction manual

Features and Services
Power Failure Transfer (PFT)
Description
This feature provides service to and from the CO for a limited number of prearranged single-line
voice terminals during a commercial power failure (or when voltage drops below 90 volts for longer
than 250 milliseconds) and during other service interruptions. Any loop start or ground start trunk
may be arranged to terminate at a specific station on a one-to-one basis. When a failure occurs,
these prearranged connections are made, bypassing the system and connecting terminals directly
to the CO trunks. System features and restrictions are not available during this time.
The system supports up to four Emergency Transfer Units (ETUs). Each ETU can provide up to five
voice terminals with direct connection to CO trunks.
When the system connects to dial pulse trunks, only rotary sets may be used to support Power
Failure Transfer (PFT). When the system interfaces the CO via touch-tone trunks, touch-tone
single-line voice terminals are used as PFT stations.
When power is restored, the following will be restored to their previous state:
1. Night Service mode (on or off).
2. User-programmed Flex DSS numbers.
3. PDCs signed in at a “home station” or an “away station” remain signed in there; if Forwarding
has been activated for a station, it remains in effect.
4. If a voice terminal has been removed/not removed from a DGC group, the terminal will remain
in that state.
5. User-programmed Repertory Dialing numbers.
6. All system/station features programmed through system administration.
Considerations
Power Failure Transfer provides emergency incoming and outgoing telecommunications service to
a number of predesignated single-line voice terminals.
This is particularly important for
organizations providing public services such as fire, police, medical, etc.
Hardware Requirements
The 10B Emergency Transfer Unit (ETU) in Figure 2-38 supports up to five Power Failure Transfer
(PFT) sets and a DID make-busy function. Up to four ETUs can be supported for a maximum of 20
PFT sets. The sets can be connected to selected Loop Start or Ground Start trunks. If Ground Start
trunks are used, a KS 23566,L1 Ground Start Button must be provided at each PFT set.
2-262
November 1995