Specifications

Page 2–2
FOCUS System Manual
The choice of whether or not fiber will be
available to the user for a particular link between
nodes and even whether or not a particular node
will be installed depends on the up-front planning
and economics for the installation. This section
assumes that there are no limitations to routing or
node locations, as these decisions may be
dependent on many factors.
Once you have determined the number and
location of nodes and the number and configura-
tion of links for your system, it is time to
configure the individual nodes. You will need to
know the following for each node:
• Is this part of a loop of nodes? If yes, will
automatic loop reconfiguration be imple-
mented?
•Will the service voice channel be used? If
yes, will a Party Line Order Wire scheme
be implemented?
•How many Electrical Transceiver
Interfaces are used?
•Will Hot-Standby (1+1) optics be used in
any of the transceiver interfaces?
•What are the supply voltages for the Main
and Standby (if used) Power Supplies?
• How many Fiber Optic Transceiver
Interfaces are used?
Answers to the above questions will allow you to
specify the common equipment for each node.
The section titled “Ordering Information” later in
this chapter describes how to identify a catalog
number for each node with this information.
Once you have identified the catalog number for
each chassis, the next step is to determine how
many of each type of data channel module is
required. Each chassis has 12 slots available for
channel modules, each of which occupies either
one or two slots. If your application requires more
than 12 slots, you must add an optional second, or
expansion, chassis. This will provide an additional
12 slots for channel modules.
2.2.1 Relay Applications
The FOCUS Fiber Optic system is a T1 digital
multiplexed system with specialized relay inter-
faces. These interfaces have been designed to take
the best advantage of digital fiber optics to
provide high security and high dependability for
your relay system. The FOCUS system can
provide a highly reliable channel for any relay
system on the market today, as well as any in the
foreseeable future.
Apilot wire relay system is one of the most
elegant relay systems in service today. Its past
performance, however, has been limited by the
requirements of metallic circuits and the ex-
traneous voltages that are present on the metallic
pair during a fault. The FOCUS system solves this
problem of poor channel performance of the pilot
wire.
The FOCUS system also provides a highly secure
channel for directional comparison relay systems.
It provides a module which can be keyed by a
contact and provide an output contact for up to
four relaying systems. These systems can be of
any type, such as, directional comparison
blocking, unblocking, and any of the various
transfer trip systems.
2.2.1.1 Directional Comparison Blocking
System
These systems normally are designed such that
they will accept a form A or B contact to key the
FOCUS system to an active state. This in turn
causes contact closure at the remote terminal that
can be used for blocking. Instead of inputting the
carrier start contact into a power line carrier (PLC)
transmitter, the same lead can be input to one of
the relay function inputs on the PRI channel. That
function is then transmitted to the remote end,
where an output contact can be used in the
blocking circuit. With blocking systems, you have
a choice of setting the system to block or permit
trip on a loss of channel. The traditional power
line carrier blocking system will trip if the carrier
is lost (refer to the unblocking section).