Download Proposed revision to leakage current limitations.

Telecommunications Industry Association
TR41.9.1-08-11-005
Document Cover Sheet
Project Number
PN-3-0016-RV2 (to become TIA-968-B)
Document Title
Proposed Leakage current limitations for terminal equipment
connected to a voltage source greater than 250V.
Source
Verizon
Contact
Trone Bishop
13100 Columbia Pike
Silver Spring, MD 20904
Distribution
TR-41.9.1, at Nov. meeting in Costa Mesa CA
Intended
Purpose of
Document
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Phone:
301-236-3754
Email:
[email protected]
For Incorporation Into TIA Publication
For Information
Other (describe) Notices
The document to which this cover statement is attached is submitted to a Formulating Group or subelement thereof of the Telecommunications Industry Association (TIA) in accordance with the provisions
of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of which
provisions are hereby incorporated by reference.
This document has been prepared by Verizon to assist TIA Engineering Committee TR-41. It is proposed
to the TR41.9 subcommittee as a basis for discussion and is not to be construed as a binding proposal on
Verizon. Verizon specifically reserves the right to amend or modify the material contained herein and
nothing herein shall be construed as conferring or offering licenses or rights with respect to any
intellectual property of Verizon other than provided in the statement above.
Abstract
The existing leakage current requirements in clause 4.2 of dpANS TIA-968-B are based on the
assumption that terminal equipment connects to, or is used in close proximity to, electrical power
lines having a voltage of less than 250V. In recent years, equipment has been developed that has
a direct connection to wireline carrier network interfaces and to commercial electric power lines
having a voltage greater than 250Vac. In such cases, the existing leakage current limits in dpANS
TIA-968-B may not be adequate to prevent electrical hazards to personnel of providers of wireline
telecommunications as required by 47 C.F.R. Part 68. This contribution proposes that TR41.9
study this issue, liaison with other committees if necessary, and develop technical criteria that will
prevent electrical hazards to wireline carrier personnel. “Strawman” text is proposed for inclusion
in clause 4.2 of dpANS TIA-968-B to stimulate discussion and provoke the generation of new and
better proposals.
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Telecommunications Industry Association
TR41.9.1-08-11-005
Introduction
The leakage current limitations in dpANS TIA-968-B ensure that telephone connections, such as
the T, R, T1, and R1 leads at a DS1 interface, are adequately insulated against supply voltages
within terminal equipment voltages that are hazardous to telephone company personnel. The
leakage current limitations also ensure that hazardous voltages do not appear on telephone
connections as the result of accidental contact with commercial power. The 1500V test voltage for
leakage current tests in dpANS TIA-968-B is based on commonly used criteria for testing
transformer insulation that specifies using 1000 volts plus twice the rated primary voltage. 1 Thus,
the leakage current requirements in dpANS TIA-968-B are based on the assumption that terminal
equipment connects to electrical power lines having a voltage of less than 250V.
In recent years, terminal equipment has been developed that is not only intended for direct
connection to wireline carrier networks, but also is intended for direct connection to commercial
electric power lines having a voltage greater than 250Vac.
Since the existing leakage current requirements in clause 4.2 of dpANS TIA-968-B are based on
the assumption that terminal equipment connects to electrical power lines having a voltage less
than 250V, the limitations may not be adequate to prevent electrical hazards to personnel of
providers of wireline telecommunications as required by FCC rules and regulations.2
Proposal
This contribution proposes that TR41.9 study this issue, liaison with other committees if
necessary, and develop technical criteria that will prevent electrical hazards to wireline carrier
personnel.
The following “strawman” text is proposed for inclusion in clause 4.2 of dpANS TIA-968-B to
stimulate discussion and provoke the generation of new and better proposals.
Strawman Proposal to Stimulate Discussion
Change the text of clause 4.2 of dpANS TIA-968-B3 as shown below. New text is underlined.
4.2
Leakage Current Limitations
Leakage current shall not exceed 10 mA peak at any time during the 90 second test interval
described below when the 50-60 Hz AC test voltage in table 4.1 is applied between the test points
in table 4.1.
The test voltage in Table 4.1 assumes that the terminal equipment has a rated input voltage of
less than 250V. If the input voltage of the terminal equipment is greater than 250V, then the test
voltage shall be increased to 1000V plus twice the rated voltage.
The 10 mA peak maximum leakage current limitation may be increased as described in 4.2.6 to
accommodate cable capacitance associated with multi-unit equipment.
1 TIA-TSB-31-C, TIA Telecommunications System Bulletin, Telecommunications – Telephone Terminal
Equipment – Rationale and Measurement Guidelines for U.S. Network Protection; p. 36.
2 47 C.F.R. Part 68.3
3 TR-41.9.1-08-08-002-MR2, PN-3-0016-RV2 (TIA-968-B) Draft Revision 9.0, Origination Date 9 Jul. 2008;
Scott Roleson, Hewlett-Packard Company; as revised by TR41.9.1 at its August 2008 meeting.
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