Employing sense resistor as safety fuse in limited power source applications
View Patent ↗A communication network utilizing Power Over Ethernet technology including Power Sourcing Equipment (PSE) that includes a multi-purpose device that operates as a current sensing resistor under normal electrical operating conditions and operates as a protection device, e.g., a fuse, under fault conditions, such as, an internal switch failure and an overload occurring simultaneously.
1. A method of providing power for at least one communication device in a communication network, the method comprising:
providing at least one communication device operable to transmit or receive communications over the communication network;
providing a power sourcing device, said provided power sourcing device being a limited power source;
connecting the output of said provided power sourcing device to said provided at least one communication device via communication cabling;
arranging said provided power sourcing device to comprise a general purpose resistor providing a current sensing function by which an amount of electrical current drawn by said provided at least one communication device via the communication cabling is sensed; and
selecting a value for said general purpose resistor so as to further provide a fault protection function by which the output of said provided power sourcing device is disconnected during a predetermined fault condition.
2. A method according to claim 1 , further comprising:
powering said provided at least one communication device from said provided power sourcing device via the data ports of a switch.
3. A method according to claim 1 , wherein the predetermined fault condition comprises a failure in a power switch of said provided power sourcing device and one of an overload and a short circuit condition in either or both of said provided at least one communication device and the communication cabling connecting said provided communication device and said provided power sourcing device.
4. A method according to claim 1 , wherein the predetermined fault condition comprises an open circuit condition.
5. A method according to claim 1 , wherein said provided power sourcing device is arranged as an end span power sourcing equipment.
6. A method according to claim 1 , further comprising:
sensing an amount of current drawn by said provided at least one communication device, said sensing being responsive to said general purpose resistor; and
limiting the amount of current drawn by said provided at least one communication device via the communication cabling responsive to said sensing.
7. A method according to claim 1 , further comprising:
arranging said provided power sourcing device between a data switch and said provided at least one communication device.
8. A method according to claim 1 , wherein said selected value limits the amount of current drawn by said provided at least one communication device via the communication cabling to 100 VA.
9. A method according to claim 1 , wherein said general purpose resistor is a surface mount resistor.
10. A method of providing a protected limited power source, the method comprising:
providing a limited power source arranged and configured to provide power to at least one communication device over communication cabling;
configuring said provided limited power source to comprise a general purpose resistor exhibiting a voltage across the general purpose resistor proportional to an amount of current provided to the at least one communication device; and
selecting a value for said general purpose resistor so as to provide a protection function by which power provided to the at least communication device over communication cabling is interrupted in the event of a fault condition.
11. A method according to claim 10 , wherein the predetermined fault condition comprises a failure in a power switch of said provided power sourcing device and one of an overload and a short circuit condition in either or both of the at least one communication device and the communication cabling connecting the at least one communication device and said provided limited power source.
12. A method according to claim 10 , wherein the predetermined fault condition comprises an open circuit condition.
13. A method according to claim 10 , wherein said provided limited power source is arranged as an end span power sourcing equipment.
14. A method according to claim 10 , wherein said provided limited power source is arranged as a mid-span power sourcing equipment.
15. A method according to claim 10 , further comprising:
sensing an amount of current provided to the at least one communication device, said sensing being responsive to said general purpose resistor; and
limiting the amount of current drawn provided to the at least one communication device responsive to said sensing.
16. A method according to claim 10 , wherein said selected value limits the amount of provide to the at least one communication device to 100 VA.
17. A method according to claim 10 , wherein said general purpose resistor is a surface mount resistor.
18. A method of providing power for at least one communication device in a communication network, the method comprising:
providing at least one communication device operable to transmit or receive communications over the communication network;
providing a power sourcing device, said provided power sourcing device being a limited power source;
connecting the output of said provided power sourcing device to said provided at least one communication device via communication cabling;
configuring said provided power sourcing device to comprise a general purpose resistor providing a current sensing function by which an amount of electrical current drawn by said provided at least one communication device via the communication cabling is sensed;
configuring said provided power sourcing device to comprise a power switch operable to selectively and controllably provide power to said provided at least one communication device via communication cabling; and
selecting a value for said general purpose resistor so as to further provide a fault protection function by which the output of said provided power sourcing device is disconnected during a predetermined fault condition.
19. A method according to claim 18 , further comprising:
configuring said provided power sourcing device to comprise a control section operable to control said power switch; and
controlling, via the operation of said power switch by said control section, the amount of current drawn by said provided at least one communication cabling.
20. A method according to claim 18 , further comprising:
powering said provided at least one communication device from said provided power sourcing device via the data ports of a switch.
21. A method according to claim 18 , wherein the predetermined fault condition comprises a failure in the power switch and one of an overload and a short circuit condition in either or both of said provided at least one communication device and the communication cabling connecting said provided at least one communication device and said provided power sourcing device.
22. A method according to claim 18 , wherein the predetermined fault condition comprises an open circuit condition.
23. A method according to claim 18 , wherein said provided power sourcing device is arranged as an end span power sourcing equipment.
24. A method according to claim 18 , further comprising:
arranging said provided power sourcing device between a data switch and said provided at least one communication device.
25. A method according to claim 18 , wherein said selected value limits the amount of current drawn by said provided at least one communication device via the communication cabling to 100 VA.
26. A method according to claim 18 , wherein said general purpose resistor is a surface mount resistor.