Specifications

December 2008 Page 2–3
Chapter 2. System Application and Ordering
2
2.2.1.2 Permissive and Direct Transfer
Trip Systems
A function on the Protective Relay Interface
(PRI/PRS) Module may be used to provide a
transfer trip function (permissive or direct). These
systems normally are designed such that they will
accept a form A contact to key the FOCUS system
to a trip state. This causes contact closure at the
remote terminal that can be used for tripping.
There is no need to involve the guard circuit, as
the PRI module is designed to give a trip output
only when the trip code is received. However, for
those older schemes that require a guard contact
output, there is a guard contact that can be used for
the purpose of supplying this function. For
transfer trip systems, the trip function should be
set to block when a channel is lost.
2.2.1.3 Directional Comparison
Unblocking Systems
Another function on the PRI/PRS Module may be
used to provide an unblock channel function.
These systems also are normally designed such
that they will accept a form A contact to key the
system to a trip state. This causes contact closure
at the remote terminal that can be used for trip
permission. For the unblock system, the PRI trip
function should be set to give a trip output for a
period of 150ms after a loss of channel. After the
150ms period, the system will block tripping.
2.2.2 HCB Pilot Wire System
If you want to replace the pilot wires used by an
HCB relay, we recommend that you use the
FOCUS Pilot Wire Interface Module. This module
is designed for use with Westinghouse/ABB HCB
and HCB-1 relays and the General Electric SPD
relay.
Connecting this module (via the FOCUS system)
to the existing relay terminals removes the
necessity for the metallic pilot wire, insulating
transformers, neutralizing or drainage reactors,
and lightning arrester tubes or other devices
required to compensate or condition the metallic
pilot wires. It also replaces all of the pilot wire
monitoring equipment and the dc auxiliary
transfer trip function. Full details can be found in
Chapter 17.
2.3 Ordering Information
The catalog number for a FOCUS chassis
comprises 11 characters, each in a specific
position. This number identifies the type of
chassis you are ordering, including all common
equipment, or system modules, as well as the type
of network configuration you are using. A descrip-
tion of the purpose of each catalog number
position is shown in Table 2-2.
In addition to the catalog number for the chassis,
each channel module has its own three- or six-
character catalog number.
To order one or more FOCUS chassis and the
desired channel modules, simply identify the
features or modules you want using the appro-
priate catalog numbers. Table 2-1 on the following
page shows a complete listing of the catalog
options for the FOCUS chassis, as well as a
sample catalog number. Table 2-4 shows the
catalog numbers for the individual channel
modules.
Following is a sample catalog number for a
FOCUS chassis. The first row shows the catalog
number position, while the second row shows the
character representing a sample option for that
position.
This sample number represents an order for the
following FOCUS system:
• Base Unit for T1
• Party line orderwire
•Alternate path mode (APM) with remote
node configuration (RNC)
•110/125Vdc/Vac main power supply
•110/125Vdc/Vac backup power supply
• Dual 1300 nm laser transceiver for trans-
ceiver slot one
• Single DS1 transceiver for slot two
1 2 3 4 5 6 7 8 9 10 11
F P S 1 1 A A E N 3 T