# US 7,612,975 B1 · Lightning protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,975 B1 - Document ID: US7612975B1 - Status: Granted - Kind: B1 - Application number: 10/979,658 - Filed: 2004-10-14 - Granted: 2009-11-03 - Earliest claimed: 2004-10-14 - Assignees: Nortel Networks Limited - Inventors: Ian Abraham; Keith Edwards; Mark Watkins - Web page: https://patentgrep.com/patent/US7612975B1 ## CPC - H02J 1/002: using intermediate DC-AC-DC conversion - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract A power supply line for powering electronic equipment from a power supply remote from the electronic equipment, having a balanced differential power transmission path 31 connecting the power supply 32 to the electronic equipment 13 and at least one isolating transformer 33, 34 in the power supply line, for providing isolation from ground potential rise associated with lightning surge currents. The invention has particular application to a wireless communications tower having the isolated power supply line for powering masthead electronic equipment 13, and an isolated communications link 21 between the masthead electronic equipment and a network terminal 22. ## Claims ### Claim 1 A power supply line for powering electronic equipment situated at a first location from a power supply situated at a second location remote from the electronic equipment, wherein the first location has a first local ground potential and the second location has a second local ground potential, the first location being sufficiently remote from the second location that a lightning surge current may induce a difference between the first local ground potential and the second local ground potential, the difference in potential being of a magnitude so as to risk causing damage if it were applied to the electronic equipment, the power supply line comprising a balanced differential power transmission path comprising two conductors connecting the power supply to the electronic equipment, the power supply being operable to provide a potential difference on each of the two conductors and the electronic equipment being operable to derive a potential difference between the two conductors, the power supply line further comprising at least one isolating transformer in the power supply line for providing isolation from the difference between the first and second local ground potentials associated with lightning surge currents, wherein the power supply line is not connected to the first or second local ground potential so as to achieve isolation from ground potential rise associated with lightning surge currents. ### Claim 2 (depends on 1) A power supply line as claimed in claim 1, wherein a first isolating transformer is located at a power supply terminal of the power transmission path and a second isolating transformer is provided at an electronic equipment terminal of the power transmission path. ### Claim 3 (depends on 1, 2) A power supply line as claimed in claims 1 or 2, wherein the at least one isolating transformer has shielding extending between input and output windings of the transformer. ### Claim 4 (depends on 1) A power supply line as claimed in claim 1, wherein the balanced differential power transmission path comprises at least two cables for transmitting an alternating current. ### Claim 5 (depends on 4) A power supply line as claimed in claim 4, wherein the at least two cables are for transmitting an alternating current having a frequency of greater than common 50/60 Hz mains supplies. ### Claim 6 (depends on 5) A power supply as claimed in claim 5, wherein the at least two cables are for transmitting an alternating current having a frequency in the range 360 Hz to 440 Hz. ### Claim 7 (depends on 1) A power supply line as claimed in claim 1, for powering masthead electronic equipment of a wireless communications tower. ### Claim 8 (depends on 7) A power supply line as claimed in claim 7, wherein the wireless communications tower is further provided with an isolated data communications link to the masthead electronic equipment. ### Claim 9 (depends on 8) A power supply line as claimed in claim 8, wherein the isolated data communications link is at least one of an optical fibre link, a wireless link and an Ethernet link. ### Claim 10 (depends on 1) A power supply line as claimed in claim 1, adapted to operate at a sufficiently low voltage to allow safe installation in hazardous environments operate. ### Claim 11 (depends on 1) A power supply line as claimed in claim 1, comprising an isolated DC power supply, using a single transformer within a conventional switched mode DC-DC converter to achieve isolation. ### Claim 12 A wireless communications tower comprising an isolated power supply line for powering masthead electronic equipment situated at a first location from a power supply situated at a second location remote from the electronic equipment, wherein the first location has a first local around potential and the second location has a second local around potential, the first location being sufficiently remote from the second location that a lightning surge current may induce a difference between the first local ground potential and the second local ground potential, the difference in potential being of a magnitude so as to risk causing damage if it were applied to the electronic equipment, the isolated power supply line comprising a balanced differential power transmission path comprising two conductors connecting the power supply to the electronic equipment, the power supply being operable to provide a potential difference on each of the two conductors and the electronic equipment being operable to derive a potential difference between the two conductors, the tower further comprising at least one isolating transformer in the power supply line for providing isolation from the difference between the first and second local ground potentials associated with lightning surge currents, wherein the isolated power supply line is not connected to the first or second local ground potential so as to achieve isolation from ground potential rise associated with lightning surge currents, and an isolated data communications link between the masthead electronic equipment and a network terminal. ### Claim 13 A method of powering electronic equipment situated at a first location over an isolated power supply line from a power supply situated at a second location remote from the electronic equipment, wherein the first location has a first local ground potential and the second location has a second local around potential, the first location being sufficiently remote from the second location that a lightning surge current may induce a difference between the first local around potential and the second local around potential, the difference in potential being of a magnitude so as to risk causing damage if it were applied to the electronic equipment, the method being for providing isolation from the difference between the first and second local ground potentials associated with lightning surge currents, comprising the steps of: a. providing a balanced differential power transmission path connecting the power supply to the electronic equipment, the path comprising two conductors; b. providing at least one isolating transformer in the power supply line; and c. supplying power from the power supply to the electronic equipment through the balanced differential power transmission path and the at least one isolating transformer by providing, at the power supply, a potential difference on each of the two conductors and deriving, at the electronic equipment, a potential difference between the two conductors, wherein the isolated power supply line is not connected to the first or second a local ground potential so as to achieve isolation from ground potential rise associated with lightning surge currents. ### Claim 14 (depends on 13) A method as claimed in claim 13, wherein the step of providing at least one isolating transformer comprises the step of providing a first isolating transformer at a power supply terminal of the power transmission path and a second isolating transformer at an electronic equipment terminal of the power transmission path. ### Claim 15 (depends on 13) A method as claimed in claim 13, wherein the step of providing at least one isolating transformer comprises the step of providing at least one isolating transformer with shielding extending between input and output windings of the transformer. ### Claim 16 (depends on 13) A method as claimed in claim 13, wherein the step of providing a balanced differential power transmission path comprises providing at least two cables adapted for transmitting an alternating current. ### Claim 17 (depends on 16) A method as claimed in claim 16, wherein the step of providing at least two cables comprises providing at least two cables adapted for transmitting an alternating current having a frequency greater than common mains 50/60 Hz and the step of providing at least one isolating transformer comprises providing at least one isolating transformer for transmitting an alternating current having a frequency greater than common mains 50/60 Hz. ### Claim 18 (depends on 13) A method as claimed in claim 13, adapted for powering masthead electronic equipment of a wireless communications tower. ### Claim 19 (depends on 18) A method as claimed in claim 18, having a further step of providing the wireless communications tower with an isolated data communications link to the masthead electronic equipment. ### Claim 20 (depends on 19) A method as claimed in claim 19, wherein the step of providing the wireless communications tower with an isolated data communications link comprises providing at least one of an optical fibre link, a wireless link and an Ethernet link. ### Claim 21 (depends on 13) A method as claimed in claim 13, adapted to operate at a sufficiently low voltage to allow safe installation in hazardous environments. ### Claim 22 (depends on 13) A method as claimed in claim 13, wherein the step of providing a balanced differential power transmission path comprises providing an isolated DC power supply; and the step of providing at least one isolating transformer in the power supply line comprises providing a single transformer within a switched mode DC-DC converter to achieve isolation.