Power distribution system with low complexity and low power consumption
View Patent ↗The invention relates a system for controlling distribution of power to load elements via network connections (e.g. LAN). Low cost luminaires or other load elements can be powered via LAN connections (e.g. by power over Ethernet (PoE)) without featuring an Internet Protocol (IP) node. This is attractive because with such a system the installation cost down benefits of PoE can be applied also to installations that do not require advanced controls. This means that to switch them on or off, the power supply on the LAN port of the switch must be enabled or disabled. When load elements and load controllers (e.g. lighting controllers or light switches) are connected to the same switch, they are automatically paired to each other. This can be achieved through use of a network management protocol capability that some network switches have. This allows for easy installation and automatic intuitive commissioning.
1. A control device for controlling distribution of power to load elements via network connections, said control device being adapted to issue control commands of a network management protocol to a network switch in order to switch on or off selected local area network, LAN, ports of said network switch, through which said power is supplied to respective ones of said load elements, wherein said network management protocol is the Simple Network Management Protocol, SNMP;
wherein said control device comprises a wall switch or a sensor for detecting presence of people and initiating a power switching operation in response to a result of detection, or a user interface for manually initiating said power switching operation, or a building management system for controlling lighting based on sensor inputs; and,
wherein said control device is adapted to discover what network switch it is connected to by employing a network scan and probing for its own network address in cache tables of a network management protocol compatible network switch.
2. The control device of claim 1 , wherein said load elements are luminaires.
3. The control device of claim 1 , wherein said control device is adapted to discover said selected LAN ports by checking which layer-2 address cache tables of available LAN ports of a discovered network switch are empty or do not have a link-up.
4. The control device of claim 1 , wherein Power over Ethernet, PoE, is used for said distribution of power.
5. The control device of claim 1 , wherein said network switch is a midspan device.
6. A system for controlling distribution of power to load elements via local area network, LAN, connections, said system comprising at least one control device according to any one of claims 1 , 3 , 4 , and 5 .
7. The system of claim 6 , wherein said network switch is adapted to switch off a main power supply unit if all its LAN ports are switched off.
8. A method of controlling distribution of power to load elements via local area network, LAN, connections, said method comprising issuing control commands of a network management protocol to a network switch in order to switch on or off selected LAN ports of said network switch, through which said power is supplied to respective ones of said load elements, wherein said network management protocol is the Simple Network Management Protocol, SNMP; and,
wherein said method further comprises discovering said network switch by employing a network scan and probing for an own network address in cache tables of a network management protocol compatible network switch.
9. The method of claim 8 wherein said method further comprises discovering said selected LAN ports by checking which layer-2 address cache tables of available LAN ports of said discovered network switch are empty or do not have a link-up.
10. A computer program product comprising a plurality of program code portions, stored in a non-transitory computer readable medium, for carrying out the method according to claim 8 .