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(Continuation of Question 4/5) Motivation
New types of equipment (examples are routers, set-top units, cable modems,
ONTs, xDSL modems, and WLL) are appearing in the network. Also, different types
of equipment are being interconnected at customers' premises and the
requirements for the internal interfaces and the effects of these
interconnections need to be considered.
At least four major changes have occurred which affect the requirements of
the existing resistibility recommendations.
- The access network is rapidly changing from a traditional exchange
(switching centre) which may be kilometres from the customer to the
switching equipment being close to the customer. As an example, digital
circuits (e.g. ISDN) are being used, high-speed data services (xDSL) are
being introduced, voice can now be transmitted over the Internet and routers
with packet-switching compete with conventional switching systems.
- POTs, data and video services are being generated in the customer
building. The customer may want to route these services to other buildings.
The ports connecting to these services are usually designed for connection
to internal cables only.
- The environment where the equipment is housed is also changing.
Traditionally switching equipment has been installed in a controlled
environment with the protection installed in an MDF. With miniaturization
and changing technologies bulky rack-mounted equipment has been replaced by
small equipment, which may be installed on a wall, in a shelter or
underground with the high current protection integral to the equipment.
- Many countries have regulations regarding grade of service where the
operator can be fined if an adequate grade of service is not provided.
These changes require study to determine what steps are required to ensure
that the recommendations fit the needs of the operators and the user of the
telecommunication network.
This Question impacts climate change issues by ensuring that adequate
resistibility requirements for equipment and protective measures for
installations reduce the amount of equipment and installation damages. By
reducing damages less fossil fuels are burnt (personnel do not have to drive to
a site to repair equipment) and less manufacturing is required (less replacement
equipment is needed).
The following Recommendations, in force at the time of approval of this
Question, fall under its responsibility:
Question
The objective of this question is to produce resistibility requirements for
equipment installed in telecommunications centres, in outdoor enclosures in the
access and trunk networks and at customer premises. The sources of overvoltages
and overcurrents that may cause damage to the equipment include lightning, power
induction and mains power contacts. The types of interfaces include symmetric
pair, coaxial, dedicated power feeds and mains power ports.
Study items to be considered include, but are not limited to:
- Acceptable period for equipment recovery after application of surges
(K.20, K.21, K.44 and K.45);
- Power contact test, specifically whether a single line to earth test
should be performed (K.20, K.21, K.45 and K.44).
- Resistibility test level of ITE ports (e.g. USB, Ethernet, RS232, E1)
compared with telecommunication ports (K.21).
- Determine resistibility requirements taking into account the effects of
interconnecting equipment connected to different services e.g. mains,
symmetric pair telecommunications, services derived within the building,
CATV broadband, WLL etc.
Tasks
Tasks include, but are not limited to:
- Prepare a guide to assist in ensuring that compliance testing is done
correctly. Due to cost constraints short cuts are often taken resulting in
incomplete testing. As a result incorrect conclusions maybe drawn re
compliance.
- Maintenance and enhancement of the existing recommendations K.20, K.21,
K.44, K.45 for protection of communication equipment.
An up-to-date status of work under this Question is contained in the SG 5
Work Program (use URL as shown in the table below).
Relationships
Recommendations:
- K.11, K.12, K.27, K.28, K.35, K.36, K.66, K.67 and K.71
Questions:
- 1, 5, 6, 8, 9, 11, 12, 13, 14 and 15/5
Study Groups:
Standardization bodies:
- IEC TC 108, IEC TC 81, IEC SC 37A, IEC SC 77B WG13, CENELEC TC
81X, ETSI ERM
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