ABB Furse - ABN010 Analogue and digital telecommunications

ABB Furse - ABN010 Analogue and digital telecommunications
Application Note
Analogue and digital
telecommunications protection
Analogue and digital telecommunications protection
Overwiew
PSTN stands for Public Switched
Telephone Network.
This is basically the phone lines that
are the property of the Public
Telecommunications Operator (PTO).
Only a licensed PTO can make
connections to the PSTN line.
Protection after the NTP or PSTN
interface
The lines after the NTP are the
equivalent to the ISDN S/T interface,
protection can be installed on these
lines without permission of the PTO.
The type of protection on standard
analogue systems after the NTP varies
depending on the system.
Protection
Terminating the PSTN line is a
Network Termination Point (NTP).
PSTN interface
When installing an analogue system the
PTO will install a standard PSTN line
(see Figure 1).
The NTP on this line can vary depending
on the system type required by the end
user. It is usually a master wall socket
for domestic phone lines. For complex
telecommunication installaions, it is
usually a connection frame
or Private Branch Exchange (PBX).
There are two ways to protect
telecommunication systems, either
protection on the PSTN interface
or protection after the NTP.
Protection on the PSTN interface
Connections to the PSTN lines should
only be made by licensed PTO’s or with
prior permission of the PTO who owns
the system. However if this is permitted,
PSTN lines can be protected by using
Furse wire-in protectors ESP SL TN,
ESP TN or the 4-way ESP TNQ.
See Figure 1.
The PSTN lines and the NTP remain the
property of the PTO.
Figure 1: Protection on analogue systems
Note: With normal domestic installations the NTP would usually only be
a master wall socket, connection frames and PBX’s are usually only used
in business or other complex telecommunication installations.
2 AN010 | Application Notes - Analogue and Digital Telecommunications Protection
Furse wire-in ESP SL TN, ESP TN
(or 4-way ESP TNQ) can be used in-line
with telephone wiring.
The British style jack plug-in connection
ESP TN/JP can be used in between the
telephone equipment and a wall socket.
Similarly the RJ11 jack plug-in
connection ESP TN/RJ11-#/6 (#
variants are 2, 4 and 6 wire) can
be used in between the telephone
equipment (usually modems or non-UK
phones) and a wall socket.
If an LSA-Plus PBX board is used,
ESP KT1 protectors and an ESP KE10
earth bar (or the 10-way ESP K10T1
protectors) can be used. See Figure 1.
Analogue and digital telecommunications protection
Overwiew
ISDN stands for Integrated Services
Digital Networks. For ISDN
installations licensed Public
Telecommunications Operators
(PTO’s) will use normal PSTN
(analogue) lines then terminate them
with a NT1 device, this is referred
to as the Network Termination Point
(NTP).
After the NTP the lines are digital and
are routed to ISDN data/voice
terminals or ISDN modems.
Only a licensed PTO can make
connections to the U interface side of
the NT1 termination device.
The S/T interface is the output lines
of the NT1 termination device, this
side of the NT1 is the property of the
consumer, and therefore protection can
be installed without permission
of the PTO.
All ISDN devices connect to this
interface in order to communicate over
ISDN.
S/T interface or U interface?
In Europe the ISDN wall jacks are S/T
interfaces, and ISDN modems and data/
voice terminals connect to this interface.
When installing an ISDN system the
PTO will install a U interface (see Figure
2).
Protection
The U interface remains the property
of thecPTO and for basic rate ISDN
installation is a 2-wire line that connects
to a NT1 termination device. This
termination device will also be
installed by, and remain the property of,
the PTO.
There are two ways to protect telecoms
systems, either protection on the U
interface or protection on the S/T
interface.
Protection on the U interface
Installation at this point offers the best
possible protection, as all the
equipment after, including the NT1
termination device, is protected.
Connections to the U interface should
only be made by a licensed PTO or with
prior permission of the PTO who owns
the system.
Usually the U interface is routed straight
to the NT1 device, the Furse ESP SL
TN, ESP TN or the 4-way ESP TNQ
protector can be installed in series
before the NT1 device. See Figure 2.
Protection on the S/T interface
The output (S/T interface) terminals
of NT1 devices are usually RJ45
connectors. In this case Furse ESP
ISDN/RJ45-4/8 (4-wire) or Furse
ESP ISDN/RJ45-8/8 (8-wire) protectors
should be used to protect each line
going to equipment requiring protection
(see Application Note AN002 for
information on ISDN/RJ45 protectors contact Furse).
The outputs from an NT1 device may go
through an LSA-Plus panel before
connection to ISDN data/voice
terminals, in this case Furse ESP KT2
protectors and an ESP KE10 earth bar
(or the 10-way ESP K10T2 protectors)
can be used. See Figure 2.
Figure 2: Protection on analogue systems
Note: The diagram above refers to a Basic Rate ISDN interface.
A Primary Rate (30 channel) ISDN interface, although more
complex, can be protected in exactly the same way.
Application Notes - Analogue and Digital Telecommunications Protection | AN010 3
ABB Furse
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Nottingham
NG2 1EB
Tel: +44 (0) 115 964 3700
Fax: +44 (0) 115 986 0071
Sales Tel: +44 (0) 333 999 9900
Sales Fax: +44 (0) 333 999 9901
E-Mail: enquiry @ furse.com
Note: We reserve the right to make technical changes or modify
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