| US 7,508,930 B2 | ||
| Technique for independent ground fault detection of multiple twisted pair telephone lines connected to a common electrical power source | ||
| Scott L. Smith, Madison, Ala. (US); and Steven M. Robinson, Madison, Ala. (US) | ||
| Assigned to Adtran, Inc., Huntsville, Ala. (US) | ||
| Filed on Jan. 20, 2004, as Appl. No. 10/760,996. | ||
| Prior Publication US 2005/0163308 A1, Jul. 28, 2005 | ||
| Int. Cl. H04M 1/00 (2006.01) | ||
| U.S. Cl. 379—395.01 [379/412] | 11 Claims |
| 1. A method of delivering span power by way of a plurality of telecommunication wireline segments to respective ones of a
plurality of remote telecommunication terminals, said method comprising the steps of:
(a) coupling said plurality of telecommunication wireline segments to a span power bus, so that span power is coupled from
said span power bus to said plurality of telecommunication wireline segments;
(b) coupling respective ones of said plurality of telecommunication wireline segments to respective ones of said plurality
of remote telecommunication terminals, so that said span power is delivered by said plurality of telecommunication wireline
segments to said respective ones of said plurality of remote telecommunication terminals;
(c) coupling respective ones of said plurality of telecommunication wireline segments to respective ones of a plurality of
ground fault detection and isolation circuits, a respective ground fault being capable of causing electrical current in excess
of normal load current to flow in a remote telecommunication terminal that is connected to the respective telecommunication
wireline segment in which the ground fault has occurred, and causing a reduction in said span power to a level that prevents
proper operation of a remote telecommunication terminal that is coupled to a telecommunication wireline segment in which no
ground fault has occurred;
(d) causing said ground fault detection and isolation circuits to monitor said plurality of telecommunication wireline segments
for the occurrence of a ground fault therein; and
(e) in response to a ground fault detection and isolation circuit detecting, in step (d), the occurrence of a ground fault
in an associated telecommunication wireline segment to which said ground fault detection and isolation circuit is coupled,
causing said ground fault detection and isolation circuit to decouple and isolate said associated telecommunication wireline
segment from said span power bus, so as to prevent said reduction in said span power being delivered by others of said plurality
of telecommunication wireline segments, in which no ground fault has been detected as having occurred, to remote telecommunication
terminals coupled thereto, thereby preventing misoperation of said remote telecommunication terminals coupled to said others
of said plurality of telecommunication wireline segments, wherein step (d) comprises the steps of:
(d1) at said ground fault detection and isolation circuit, measuring a first parameter representative of current flowing in
a first segment portion of said associated telecommunication wireline segment to said remote telecommunication terminal, and
measuring a second parameter representative of current flowing in a second segment portion of said associated telecommunication
wireline segment from said remote telecommunication terminal, and
(d2) at said ground fault detection and isolation circuit, in response a difference in said first and second parameters, providing
an output representative of the occurrence of a ground fault in said associated telecommunication wireline segment, and wherein
step (e) comprises causing said ground fault detection and isolation circuit to decouple, and thereby isolate, said associated
telecommunication wireline segment from said span power bus, in response to step (d1) providing said output representative
of the occurrence of a ground fault in said associated telecommunication wireline segment.
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