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POWER FAILURE TRANSFER (PFT)
Description
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 logged in at a ’’home station” or an ’’away station’’ remain logged in there.
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.
Interactions
None
Administration Requirements
None
Hardware Requirements
The 10B Emergency Transfer Unit (ETU) in Figure 2-35 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
2-189